Last I heard we should see new nvidia cards mid to late first quarter next year. New AMD cards possibly this year, but more likely early to mid first quarter.
I've been checking for news updates probably every other day on Haswell, Ivy Bridge, Kepler (NVIDIA GTX600 series), and Southern Islands (AMD NGC / HD 7000 series), and so far, nothing. Rumors of product ramp-ups suggest Q1 2012 for the GPUs, but no benchmark leaks or anything suggest they only have chips and haven't finalized boards yet. Or maybe they're ready, but they suck so bad that whatever company has a working product is pulling a Bulldozer-class cover up.
Early Southern Island (AMD Graphics) might be released just before/after New Years. But since they build from the ground up, don't expect the higher-end ones until a bit later, say Feb-March?
Kepler (nVIDIA) will be released later yet.
I personally think AMD will reclaim the throne. Again.