Hi – I have a IOGear GWU625 adapter which uses r8712u driver (compiled from rpi's github). On Debian 2012-04-19, I had been using successfully from console via wicd-curses and tested ok with all 3 wired keyboards I have. Tested ok either connected directly or to powered hub. TP1/TP2 steady at 5.15V.
Moving beyond the console, I finally & launched LXDE today and attached a mouse to discover my adapter stopped working and smsc95xx register read/write errors started occurring. I've tried two different wired USB mice and different permutations of connections, via powered hub and also direct. Regardless, wifi adapter fails when all 3 (kb, mouse, wifi) are connected.
I can provide more detail for my individual problem, but I'm curious to know of other people's experience using wifi along with keyboard and mouse at the same time.