IIRC it became the "Wall of SuperPowers" (from its former Wall of Shame) — indicating more than 50% of tracked packages being P3 compatible — around mid-december 2012.
There's been a real change, even from 6 months ago when I last considered Python 3.0.
Apart from NLTK (A port is underway) everything I use currently has been ported which was a surprise. Time to start thinking about making the move I think.
Guido put out a 5 year transition plan. I think we are coming to the tail end of that and now the move is happening to Python 3.