Along with all the new lenses, Nikon have (finally) got around to officially announcing the D3100 which has had almost all its specs leaked out in the past 3 months.
It's actually a surprisingly strong update with a brand new 14.2MP sensor with expanded ISO range (up to 12,800), a revised AF system which now adds point illumination in the viewfinder (why this wasn't there before I don't know!) and a whole new AF mode called "constant" (AF-F) to complement the new 1080p HD movie mode (which also means this cheapest Nikon gets live view).
DPReview have a full preview
here