If so, does anyone know when it's supposed to be available? Are there any other 'pro' quality compact cameras people might recommend?
According to this, it will be announced 2010-08-19: http://canong12.com/
As this information will be useless in only two weeks, and information about specific camera models is available elsewhere, I'll try to add some more general thoughts:
If there is a new camera release imminent, you may want to wait for it, otherwise it's just a question of whether you want a camera now or if you want to wait for some specific feature.
There are new and better cameras released all the time, so if you want to wait for the best camera, you will wait forever. You just have to settle for good enough. If you buy a camera, and see that after a while there is a new and better model released, that doesn't make your current camera any less good.
You may even look at buying the older model when the newest is released, or a used camera. You may even find the previous model in a more expensive segment at the same price as the newest in the segement you first aimed at.
If you wait until after the launch of the G12, you may well be able to pick up a G11 at a reduced price as shops try to get rid of "old" stock.
(Personally, I have my sights (and budget) set on a reconditionned G9).
I don't know when the G12 is coming out, but they usually come out around Photokina time, in one month. I'd wait for the G12 really.
As far as a 'pro' quality compact, there isn't one really. Pros use compacts as a companion camera, but there is no competition whatsoever between a compact and a dslr. I wouldn't even start trying to compare them, they serve two different purposes and markets.
The G11 is an excellent compact camera though, the G12 will probably be a good one too.