The whatsnew/3.0.rst document claims

"It is not recommended to try to write source code that runs unchanged
under both Python 2.6 and 3.0; you’d have to use a very contorted coding
style, e.g. avoiding print statements, metaclasses, and much more. "

This is no longer true, since 2.6 now has much backwards compatibility,
including fopr print statements and unicode, so it's prefectly possible
and not at all contorted to support both any longer.

I'd recommend that the above statement is changed to "under both Python
2.5 and 3.0" or simply removed.