The Canon S90 has been discontinued and the new version, the S95, is available at Adorama and B&H for $30 less than the S90. Good preliminary review here: http://www.kenrockwell.com/canon/s95.htm
Also, I just spent a week in Alaska traveling with two people who had the G11. Nice camera but, for me, it falls out of the middle. It's too big for shirt pockets and gear slings so I won't carry it on climbs, and the additional features it offers (manual control of aperture and shutter speed) over the S95 are meaningless in a camera without direct shutter control. The G11 is plagued by the same problem that plagues every PHD camera: shutter lag. They don't go off when you push the button.
If you're worried about the lack of a hand grip, you can build one up with Plast-Aid (http://www.plast-aid.com/) and cover it with Bulldog tape.