Comment 20 for bug 368661

Hi Marcelo. This is not a bug in Ubuntu, it's a configuration issue on your machine.
You have "switch_windows = disabled" in your metacity gconf and it should be "switch_windows = <Alt>Tab".

You might have had this already in intrepid without noticing because back then you were using the compiz window manager instead of metacity (however in 9.04 we disabled DRI on your chipset due to nasty bug so you fell back from using compiz to metacity). If you're interested in the details of this, check out this bug:
https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-intel/+bug/317457