Coming in the second half of 2011, Kepler is the replacement for the current 40nm Fermi GPU... The next architecture will be based on the 22nm Maxwell GPU, coming in 2013
One thing I couldn't fit into that piece: the reason Kepler is called Kepler. Kepler was the assistant/colleague of Tycho Brahe. The astronomer kept detailed notes, but Kepler was the one who collated the data and made the calculations that produced discoveries from them... very appropriate for GPU computing.