For a start-
0.8.0 is not yet done. Hopefully out by the end of November.
— Johan Bernhardsson (@jbernhardsson) October 28, 2013
And Tommaso has been working on caves!
Key to the heatmap- shows how old/close to being written to disk are the chunks, red = active, yellow = soon deleted! If you travel too far (in the infinite world we presume) areas will get deleted…