Comment 6 for bug 289356

To follow up, I've had great success with wicd:

http://wicd.sourceforge.net/

I replaced NetworkManager with wicd around a week after reporting this bug and the problem has occurred only once since then. The wireless connection is also much more stable and doesn't drop out and reassociate as frequently (or at all, really) as when using NetworkManager. I recommend others try wicd as it has more-or-less solved the problem for me.