From what I've read of Python 3, it's a change for the good. It makes the API more consistent and removes a lot of deprecated cruft. I've used 3 to write a few new scripts in the past few weeks and didn't run into anything that tripped me up. I have a bunch of existing scripts running as cron jobs with Python 2.5, but I haven't had the time to test them with the new API. It probably won't be a big deal to move them over, since I see little functionality in the change documentation that is used in those scripts.
I wish Java had spent less effort on backward compatibility and more on actually improving the language, so the Python effort is the right way, IMHO.
And the Perl designers don't worry much about backward compatibility either.
q1: Isn't it amazing that God could create the universe in only six days!
a1: nah, it was easy, no installed base