Description:
MODULES=(!floppy) seems to have no effect. The floppy module gets loaded anyway. I don't know if it's udev or some other part of the init system, but I'm betting it's something to do with udev.

Additional info:
* package version(s)
udev-151-3
initscripts-2010.05-3

* config and/or log files etc.
=====BEGIN rc.conf=====
#
# /etc/rc.conf - Main Configuration for Arch Linux
#

# -----------------------------------------------------------------------
# LOCALIZATION
# -----------------------------------------------------------------------
#
# LOCALE: available languages can be listed with the 'locale -a' command
# HARDWARECLOCK: set to "UTC" or "localtime", any other value will result
# in the hardware clock being left untouched (useful for virtualization)
# TIMEZONE: timezones are found in /usr/share/zoneinfo
# KEYMAP: keymaps are found in /usr/share/kbd/keymaps
# CONSOLEFONT: found in /usr/share/kbd/consolefonts (only needed for non-US)
# CONSOLEMAP: found in /usr/share/kbd/consoletrans
# USECOLOR: use ANSI color sequences in startup messages
#
LOCALE="en_CA.UTF-8"
HARDWARECLOCK="localtime"
TIMEZONE="Canada/Eastern"
KEYMAP="us"
CONSOLEFONT=
CONSOLEMAP=
USECOLOR="yes"

# -----------------------------------------------------------------------
# HARDWARE
# -----------------------------------------------------------------------
#
# MOD_AUTOLOAD: Allow autoloading of modules at boot and when needed
# MOD_BLACKLIST: Prevent udev from loading these modules
# MODULES: Modules to load at boot-up. Prefix with a ! to blacklist.
#
# NOTE: Use of 'MOD_BLACKLIST' is deprecated. Please use ! in the MODULES array.
#
MOD_AUTOLOAD="yes"
#MOD_BLACKLIST=() #deprecated
MODULES=(!snd_hda_intel !usblp !floppy !pcspkr)

# Scan for LVM volume groups at startup, required if you use LVM
USELVM="no"

# -----------------------------------------------------------------------
# NETWORKING
# -----------------------------------------------------------------------
#
# HOSTNAME: Hostname of machine. Should also be put in /etc/hosts
#
HOSTNAME="vault"

# Use 'ifconfig -a' or 'ls /sys/class/net/' to see all available interfaces.
#
# Interfaces to start at boot-up (in this order)
# Declare each interface then list in INTERFACES
# - prefix an entry in INTERFACES with a ! to disable it
# - no hyphens in your interface names - Bash doesn't like it
#
# DHCP: Set your interface to "dhcp" (eth0="dhcp")
# Wireless: See network profiles below
#

#Static IP example
#eth0="eth0 192.168.0.2 netmask 255.255.255.0 broadcast 192.168.0.255"
#eth0="dhcp" # PCI 10/100
#eth1="dhcp" # onboard 10/100/1000
#INTERFACES=(!eth1)

# Routes to start at boot-up (in this order)
# Declare each route then list in ROUTES
# - prefix an entry in ROUTES with a ! to disable it
#
#gateway="default gw 192.168.0.1"
#ROUTES=(!gateway)

# Enable these network profiles at boot-up. These are only useful
# if you happen to need multiple network configurations (ie, laptop users)
# - set to 'menu' to present a menu during boot-up (dialog package required)
# - prefix an entry with a ! to disable it
#
# Network profiles are found in /etc/network.d
#
# This now requires the netcfg package
#
NETWORKS=(571network)

# -----------------------------------------------------------------------
# DAEMONS
# -----------------------------------------------------------------------
#
# Daemons to start at boot-up (in this order)
# - prefix a daemon with a ! to disable it
# - prefix a daemon with a @ to start it up in the background
#
DAEMONS=(syslog-ng dbus hal slim @crond iptables net-profiles !alsa @sshd @ntpdate @ddclient @openvpn cups samba)
=====END rc.conf =====

Steps to reproduce:
-add !floppy to MODULES in rc.conf
-reboot
-lsmod reveals that floppy gets loaded anyway.