Just wanted to chime in here- maybe it will help someone...
A few days ago, I switched over to cable internet and had to reset my router (Netgear N300)
Before that, I had WEP security settings and no wifi problems, using any cm7 nightly with any kernel. I'm using cm7 #111 and 6/18 kernel now.
After resetting the router and going through the network security setup again, I decided to just go with the recommended setting: WPA-PSK [TKIP] + WPA2-PSK [AES]
Everything else in my house could connect except my nook. I tried renaming the device, forgetting all connections, turning off network location, etc. and still couldn't connect. (It seemed to connect, but immediately got bumped/dropped, and cycled like that a few tines before giving up.)
When I set up a guest network on the same router, but this time used WPA-PSK [TKIP] security, it connected right away.
I know close to nothing about wireless networking, but figured I'd mention it. Hopefully that helps....