It is certainly worth waiting to see what is announced in the next week. I don't expect more than the usual minor upgrades that will raise the price by 20%, so buying a G12 on sale is not a bad idea. If smething earthshaking comes out, I'd consider replacing my G11, but I'm pretty skeptical. The P7700 only goes to ISO 1600, and I use my G11 at ISO 3200 with usable results, so I'm wondering why it is claimed as a better sensor.
I hope Nikon's new P7700 is a good camera, Nikon has not produced any spectaular point and shoot cameras since about 2000 when I bought my CP990. I still have it, and it still performs. Its the lens that makes a difference, it was made in Japan by Nikon, not in China.