Hey Jonathan! Welcome aboard. I think I recognize your name from MU-43.
I have the NEX3 and just played with a EPM1 at Best Buy today. Both are quite portable (as far as large sensor cameras are concerned), but the NEX3 is much easier to hold thanks to the grip. If you don't plan to tweak settings on the fly a lot, either camera's menu and interface system is "satisfactory", IMO. The LCD of the NEX3 is much better as it's bigger, more detailed, and brighter. Arguably, the NEX's have one of the better LCD's in the market. The NEX3 will invariably handle high ISO a little bit better due to the larger sensor, but it also has a stronger AA filter. So at low ISO, the EPM1's photos might seem a little sharper, all other things being equal. The NEX3 also has multi-shot noise reduction, which works surprisingly well. Using the multi-shot noise reduction, you get about 1 stop of better noise signature (i.e. ISO 12800 looks like it's 6400). The EPM1 has more lenses, and has at least three pancake lenses to choose from. Plus, with the Panasonic X lens coming out soon, that's another small lens in the m4/3 lineup. IMO, the Sony 16mm gets a bad rap. I personally like the lens, and get good results out of it. I don't think it's worse or better than the Pany 14/2.5.
That all being said, I'm dying to pick up one of the new Pens, and I'm actually leaning towards the EPM1 now. I still like the NEX3 (as well as most of my cameras), but that tiny little thing with fast AF just looks like a good camera for me to throw in the bag, and have it with me all the time. If I get the EPM1, I also plan to use it with the 14/2.5 most of the time.
Decisions, decisions!!!