I have lots of references and books for Python 2.x. I am looking forward to upgrading them and doing lots of reading for the upcoming Python 3.0 release.
As usual, the official Python 3.0 docs are great:
There is already a Python 3.0 book online by Swaroop C H:
A Byte Of Python
I also just pre-ordered Mark Summerfield's printed book on Python 3.0:
Programming in Python 3: A Complete Introduction to the Python Language
Hopefully lots more books and docs on Python 3.0 are coming soon.