No. They haven't even been hinted at really. Microsoft are pushing Natal as the next big thing and Sony are going to be supporting the PS3 for at least another 4 years, they still support and develop games for the Playstation 2.
I wonder if Microsoft will release a slimmer version of the 360 though I very much doubt it, they didn't with the original Xbox so I see no reason as to why they would now. Nintendo will probably be the first of the 3 big console makers to bring out a new machine, probably something along the lines of a Wii with current generation graphics, instead of games that look like they came from the 6th gen era.