Honestly i wouldn't be surprised to see new consoles announced in 2012, or 2013 at the latest.
As for what new consoles could offer user's i would expect things like the Wii to go HD while the 360 and PS3 get additional RAM (at least 8x the RAM or 4gb minimum), faster disk reads - think 12x faster for PS3 (24x blu-ray drive), refined OS and features out of box (all games supporting motion controls / cross game voice chat, etc).
Overall i would expect the next-gen of consoles to aim to provide consumers with just enough reasons to shell out $299 or $399 for the new box. While SONY and Microsoft break-even or even profit on hardware as we have really reached the point where the power race has reached the end of the line and nobody is going to care which console "look better" when 99% of the game is identical.
