Regarding the 360, there's the awesome Kameo. Viva Pinata and a new Banjo game coming up. But I don't think it's really a console best suited for kids, especially with the early hardware issues.
According to a survey about 87% of PS3 owners watch Blu-Ray movies, suggesting a remarkable high percentage of HDTV users and thus very likely a mature user base.
The games I personally look most forward to are Resistance 2, Killzone 2 and God of War 3. But I love many Mario games as well, IMO Mario64 and Super Mario World were family games rather than specifically kids orientated games, that would be something like Pokemon or Putt-Putt.