mpf, i think i must not do something right because it doesn't work for me.
WiFi is on, s2u2 is off, no screenlock on, in the settings i unchecked "shut down if no use during ...
in the first 30-40 seconds, no problem, it all works fine, and after a minute or so, hop, wifi is off.
(sorry for my bad english, i'm a frog eater)
Proud HTC Sensation owner