After resuming from suspended state, my wifi seems to never be able to reconnect to networks. It keeps searching and trying to connect, but then fails. The list of networks never seems to update either.
This is Ubuntu 9.04, on a Lenovo T61 with Atheros 802.11b/g card.
My last resort has been to reload the kernel driver after resuming and then run:
/etc/init.d/NetworkManager restart
...but this is less than ideal ;-)