For some reason, the suspend and resume in Karmic (Ubuntu 9.10) fails to restart wireless properly on one of my laptops. According to lspci the card is a RealTek RTL8101E/RTL8102E . Everything else works ok, and the failure is intermittent - maybe one resume fails out of three or so. If you have the same problem, you can try the following before restarting your machine:
# cd /etc/init.d
# ./networking restart
# ./network-manager restart
This seems to sort the problem out, most of the time. Hopefully the Lynx is going to fix this.