Based on the specs, I will say that Nikon has done a great job on the entry level 3100.
I was in Manhattan and looked in on the Sony store and then went online and checked the specs for the to be released A380, because of the built in image stabilization and 16M pixels, I would say that the Sony is an even better entry level camera.
I was around when the Canon AE1 was introduced and the competition between the companies really made for some good equipment.
I hope Nikon rises to the challenge with their D700 replacement, but from the looks of Sony's releases, I think they have their work cut out.