Description:
It seems that gspcav1 is not compatible with new kernels. See the end of additional info for more information.

Additional info:
Here is the PKGBUILD file that I am using; I had to edit it because
the maintainer of this package has not yet changed the dependencies to
kernel26-fbcondecor 2.6.30.1-1:

# $Id: PKGBUILD,v 1.3 2008/01/26 15:48:21 tpowa Exp $
# Maintainer: Varun Acharya <varun@archlinux.org>
# Contributor: Giovanni Scafora <linuxmania@gmail.com>
# Contributor: Daniel Isenmann <daniel.isenmann@gmx.de>
#
# This PKGBUILD is based on the PKGBUILD of gspcav1 in ABS.
# The _kernver was changed to make use of gspca1 drivers for
kernel26-fbcondecor.
# Contributor: Ning Bao <phabulosa@gmail.com>

_kernver=2.6.30-fbcondecor
pkgname=gspcav1-fbcondecor
pkgver=1.00.20
pkgrel=3
pkgdesc="gspcav1 for kernel26-fbcondecor - A kernel module with
support to 260 USB webcams"
arch=('i686' 'x86_64')
url="http://mxhaard.free.fr"
license=('GPL2')
depends=('kernel26-fbcondecor>=2.6.30' 'kernel26-fbcondecor<=2.6.31')
install=gspcav1.install
source=(http://mxhaard.free.fr/spca50x/Download/gspcav1-20071224.tar.gz)
md5sums=('14853ba1f4edc1e685039fca56e5ebf2')

build() {
cd $startdir/src/gspcav1-20071224
sed -i -e "s/KERNEL_VERSION = .*/KERNEL_VERSION = ${_kernver}/" Makefile
make || return 1

#Install kernel module
install -D -m644 gspca.ko
$startdir/pkg/lib/modules/$_kernver/kernel/drivers/media/video/usbvideo/gspca.ko
sed -i -e "s/KERNEL_VERSION='.*'/KERNEL_VERSION='${_kernver}'/"
$startdir/*.install
}


Here is the gspcav1.install file that I am using; again, I have edited
it for dependencies:

# arg 1: the new package version
post_install()
{
KERNEL_VERSION='2.6.30-fbcondecor'
/sbin/depmod -ae -v $KERNEL_VERSION > /dev/null 2>&1
}

# arg 1: the new package version
# arg 2: the old package version
post_upgrade()
{
KERNEL_VERSION='2.6.30-fbcondecor'
/sbin/depmod -ae -v $KERNEL_VERSION > /dev/null 2>&1
}

# arg 1: the old package version
pre_remove() {
/sbin/rmmod gspca > /dev/null 2>&1
}

# arg 1: the old package version
post_remove()
{
KERNEL_VERSION='2.6.30-fbcondecor'
/sbin/depmod -ae -v $KERNEL_VERSION > /dev/null 2>&1
}

op=$1
shift
$op $*


Here is the log of my attempted installation:

[aaron@betabeta gspcav1-fbcondecor]$ makepkg -cs
==> Making package: gspcav1-fbcondecor 1.00.20-3 i686 (Wed Jul 8
12:06:56 EDT 2009)
==> Checking Runtime Dependencies...
==> Checking Buildtime Dependencies...
==> Retrieving Sources...
-> Found gspcav1-20071224.tar.gz in build dir
==> Validating source files with md5sums...
gspcav1-20071224.tar.gz ... Passed
==> Extracting Sources...
-> bsdtar -x -f gspcav1-20071224.tar.gz
==> Removing existing pkg/ directory...
==> Entering fakeroot environment...
==> Starting build()...
make -C /lib/modules/2.6.30-fbcondecor/build
SUBDIRS=/home/aaron/src/gspcav1-fbcondecor/src/gspcav1-20071224 CC=cc
modules
make[1]: Entering directory `/usr/src/linux-2.6.30-fbcondecor'
CC [M] /home/aaron/src/gspcav1-fbcondecor/src/gspcav1-20071224/gspca_core.o
/home/aaron/src/gspcav1-fbcondecor/src/gspcav1-20071224/gspca_core.c:54:27:
error: asm/semaphore.h: No such file or directory
In file included from
/home/aaron/src/gspcav1-fbcondecor/src/gspcav1-20071224/gspca_core.c:845:
/home/aaron/src/gspcav1-fbcondecor/src/gspcav1-20071224/utils/spcausb.h:
In function ?spca5xxRegRead?:
/home/aaron/src/gspcav1-fbcondecor/src/gspcav1-20071224/utils/spcausb.h:95:
error: implicit declaration of function ?info?
/home/aaron/src/gspcav1-fbcondecor/src/gspcav1-20071224/utils/spcausb.h:
In function ?spca_set_interface?:
/home/aaron/src/gspcav1-fbcondecor/src/gspcav1-20071224/utils/spcausb.h:278:
error: implicit declaration of function ?warn?
In file included from
/home/aaron/src/gspcav1-fbcondecor/src/gspcav1-20071224/gspca_core.c:853:
/home/aaron/src/gspcav1-fbcondecor/src/gspcav1-20071224/Sunplus-jpeg/sp5xxfw2.h:
In function ?sp5xxfw2_init?:
/home/aaron/src/gspcav1-fbcondecor/src/gspcav1-20071224/Sunplus-jpeg/sp5xxfw2.h:122:
error: called object ?info? is not a function
/home/aaron/src/gspcav1-fbcondecor/src/gspcav1-20071224/Sunplus-jpeg/sp5xxfw2.h:136:
error: called object ?info? is not a function
/home/aaron/src/gspcav1-fbcondecor/src/gspcav1-20071224/Sunplus-jpeg/sp5xxfw2.h:141:
error: called object ?info? is not a function
/home/aaron/src/gspcav1-fbcondecor/src/gspcav1-20071224/Sunplus-jpeg/sp5xxfw2.h:148:
error: called object ?info? is not a function
/home/aaron/src/gspcav1-fbcondecor/src/gspcav1-20071224/Sunplus-jpeg/sp5xxfw2.h:176:
error: called object ?info? is not a function
/home/aaron/src/gspcav1-fbcondecor/src/gspcav1-20071224/Sunplus-jpeg/sp5xxfw2.h:
In function ?sp5xxfw2_start?:
/home/aaron/src/gspcav1-fbcondecor/src/gspcav1-20071224/Sunplus-jpeg/sp5xxfw2.h:214:
error: called object ?info? is not a function
/home/aaron/src/gspcav1-fbcondecor/src/gspcav1-20071224/Sunplus-jpeg/sp5xxfw2.h:230:
error: called object ?info? is not a function
/home/aaron/src/gspcav1-fbcondecor/src/gspcav1-20071224/gspca_core.c:
In function ?spca5xx_ioctl?:
/home/aaron/src/gspcav1-fbcondecor/src/gspcav1-20071224/gspca_core.c:2463:
error: implicit declaration of function ?video_usercopy?
/home/aaron/src/gspcav1-fbcondecor/src/gspcav1-20071224/gspca_core.c:
At top level:
/home/aaron/src/gspcav1-fbcondecor/src/gspcav1-20071224/gspca_core.c:2609:
error: unknown field ?owner? specified in initializer
/home/aaron/src/gspcav1-fbcondecor/src/gspcav1-20071224/gspca_core.c:2609:
warning: initialization from incompatible pointer type
/home/aaron/src/gspcav1-fbcondecor/src/gspcav1-20071224/gspca_core.c:2611:
error: unknown field ?type? specified in initializer
/home/aaron/src/gspcav1-fbcondecor/src/gspcav1-20071224/gspca_core.c:2615:
warning: initialization from incompatible pointer type
/home/aaron/src/gspcav1-fbcondecor/src/gspcav1-20071224/gspca_core.c:
In function ?spca50x_create_sysfs?:
/home/aaron/src/gspcav1-fbcondecor/src/gspcav1-20071224/gspca_core.c:2769:
error: implicit declaration of function ?video_device_create_file?
/home/aaron/src/gspcav1-fbcondecor/src/gspcav1-20071224/gspca_core.c:2780:
error: implicit declaration of function ?video_device_remove_file?
/home/aaron/src/gspcav1-fbcondecor/src/gspcav1-20071224/gspca_core.c:
In function ?spca5xx_probe?:
/home/aaron/src/gspcav1-fbcondecor/src/gspcav1-20071224/gspca_core.c:4301:
error: incompatible types when assigning to type ?struct device? from
type ?struct device *?
make[2]: *** [/home/aaron/src/gspcav1-fbcondecor/src/gspcav1-20071224/gspca_core.o]
Error 1
make[1]: *** [_module_/home/aaron/src/gspcav1-fbcondecor/src/gspcav1-20071224]
Error 2
make[1]: Leaving directory `/usr/src/linux-2.6.30-fbcondecor'
make: *** [default] Error 2
==> ERROR: Build Failed.
Aborting...

Quoting Heiko Baums from Arch General Mailing List:
"This is an upstream issue. It seems, that gspcav1 1.00.20 doesn't work
with kernels > 2.6.26, as I've just read in a German forum.

The file semaphore.h is now located
in /usr/src/linux-2.6.30-fbcondecor/include/linux.

So the file gspca_core.c in the gspcav1-fbcondecor package needs to be
patched and "asm/semaphore.h" needs to be changed to
"linux/semaphore.h".

As a workaround you can add this line to your PKGBUILD:
sed -i "s:asm\/semaphore.h:linux\/semaphore.h" gspca_core.c"

Steps to reproduce:
1. Install the kernel26-fbcondecor package
2. Attempt to install the gspcav1-fbcondecor package