This isn't help, just a me too. I have a Lenovo W510 running F17. I've been running since the alpha a couple of months back, and this has only recently starting plaguing me (since 14th Juner 2012 or so). I find that if I sit close enough to the router to hit 100% signal, then the connection is stable. Sitting another six feet away, so that the signal strength registers 80 or so, and the connection will then drop within a couple of minutes.
Running more heavy work through the wlan0 interface seems to make it worse, so light web browsing is fine, heavy remote Lotus Notes database usage takes it out.
---------- Post added at 08:45 PM ---------- Previous post was at 08:44 PM ----------
OOo - could be this bug
---------- Post added at 09:17 PM ---------- Previous post was at 08:45 PM ----------
Try updating to the new 3.4.2 kernel (should be available right now on the main fedora repository, probably tomorrow for most of the mirrors) or use a 3.3.x kernel until it becomes available.