This does sound like a wifi driver problem, but my wifi got faster when I switched to titan's kernel; I think there were some driver improvements in 2.6.28.10.

I suspect it has to do with power saving; try turning it off to see if it fixes it; not a permanent solution but just another data point -

(from memory)
Settings->Connections
Edit your connection.. next, next, next, advanced
Flip over to the last tab, and there should be a powersaving dropdown box; select Off

If it fixes it, this may be a new bug.