Using an eeepc 1000H with rt2800pci, on F15, NetworkManager was only working with WEP non-encrypted network, no possible WPA2-TKIP .

/var/log/wpa_supplicant.log was showing the following error: 'Michael MIC failure detected'.

Googling for infos about that brought the following answers:

Logging into my router and changing the wireless encryption key for a WPA2-AES one solved the problem; wireless login to my WPA2-AES is nowfully working.

I distro-hopp a lot and never had that kind of problem previously; strange!
Hoppe that will help anybody having the same problem.