I normally shoot with a DSLR (D300), and while I love it, it's a pain to always lug the beast along. I went looking for a nice portable camera to change this. Personally, I went with the LX-3 (the 5 wasn't out at that time). I looked at the S90 (95 wasn't out) in person, and found it very nice, but too small for my hand size. I really thought I'd drop it and lose it forever pretty easily. There's a custom handgrip you can get that helps this a bit, though.
The LX5 is wider (4mm doesn't seem like much but it really is, especially for landscapes), has a bigger aperture and shorter minimum focus distance than the S95. For those reasons alone, I'd go with the LX5. The aperture is a big one, as it makes it so you don't even need to get into as high sensitivity settings that plague P&S's with noise. It also has a longer minimum shutter and faster maximum shutter speed, and shoots at twice the frames per second with a stronger flash. It's for these same reasons that I went with the LX3, and I haven't been disappointed at all.
The NEX is an interesting option, but is being debuted with stupid lens choices that severely limit its practicality for somebody who is looking for a camera ready to go for lots of things right now. Currently, there is only the 16mm 2.8 pancake and the 18-55, which is pretty limiting for the camera. You can get adapters to fit other lenses, but then, that's more cost and another thing to bring along. There's also the Sigma DP2, which, like the DP1, sounds incredible on paper but most people find infuriating in practice.
As far as the p7000 and G12, the question is do you really want the added weight for limited added functionality? It's really easy to get caught up thinking you'll use the added tele reach, but in actuality, it's very rarely used, and a larger zoom range will always lower optical quality, and typically lower the speed of the lens. One thing that these two have that is rare and very nice, though, is an optical viewfinder.
A useful review of the LX5, P7000, and S95 side by side can be found here
http://www.dpreview.com/reviews/q42010highendcompactgroup/The Thom Hogan review posted earlier is also a very good portrayal of the cameras. The fact is that today, most of the differences between higher end cameras is down to preferences in ergonomics and give-and-take-features.