At least when I write this page, upgrading the kernel of Debian (Lenny/testing) on my Asus EEE900 will stop the work of the wi-fi card. There are some steps to reactivate the wi-fi connections. Upgrading to kernel 2.6.26.x should fix the situation, afaik.
Check if madwifi drivers repository is in /etc/apt/sources.list
deb ftp://ftp.au.debian.org/debian testing main contrib non-free deb-src ftp://ftp.au.debian.org/debian testing main contrib non-free Use module-assistant to build drivers
# su
# apt-get update
# apt-get install madwifi-source
# apt-get install madwifi-tools
# m-a prepare
# m-a a-i madwifi
If not rebooting and you need to load the module
# modprobe ath_pci
It should work now, with the use of Wicd rather than Network Manager (NN doesn't support static ip).