I think the NEX-3 has only been out a week or so and the NEX-5 has yet to be released at least in the states it hasn't. I should have a NEX-5 soon after it is released (in about a week to 10 days according to Sony) but I expect it to be a point and shoot with a good lens and sensor not an easily adjustable camera.
Are you getting the 16mm? That is definitely an intriguing match to the body, quite compact. I tried out an nex3 briefly in-store last week (with the kit zoom) and was rather unimpressed. It is menu-driven to the extreme. It will be an intriguing experiment for sony - somewhat of a match up against the e-pl1.
I'm using the NEX and quite happy with it. It's DR definitely has the edge on the micro 43rds. There are a few pics on my flickr page DSC00271.jpg | Flickr - Photo Sharing! where you will see that I set my ISO to 6400 in error! I was still able to get quite usable photos. I was seated at the bull ring in the top third of the stadium and used the 18 - 55 kit lens.