Please remember there are several things this does not mean:
- Python 2.x is not obsolete. The series will continue through 2.6 (which will include backports of many Python 3 features) and probably 2.7. In fact the only guarantee is that there will be no releases after 2.9.x, as Guido has stated his dislike of the ambiguities inherent in a 2.10 release number.
- Python 3 is not ready for production work. The alpha series is expected to last a considerable length of time, and even when Python 3 comes into production (in around a year from now if Guido's original schedule is maintained) 2.6 will be the major platform.
- There should be no need to develop parallel source trees for your Python code. The 2.6 translator will have a "Python 3 warnings" mode, and if you ensure that this doesn't produce warnings you will be able to convert your code to Python 3 automatically using a conversion tool.