Python 3.0 was released last week to much commentary both pro and con. I would place myself in the pro column, for reasons best articulated here: Let’s talk about Python 3.0. The story about the monkeys beating up each other is one you'll want to file away for use someday, in the event you haven't already heard it.
The big deals seem to be the all Unicode all the time, dammit, text and extensive restructuring of little annoyances and things the Python people wish they had done differently, knowing now what they do. The fact that it's admittedly 10% slower than v2 is driving some people nutty. To others, the idea of stepping back and restructuring Python so that the foundation is more sound is a worthwhile effort, especially to those of us watching the Perl saga unfold, with no schadenfreude at all in my case (I still think Perl is awesome. Perl is the language used to build the web, and in fact the universe). Having read a very long and acrimonious discussion thread re: why the hell is Perl 6 taking so long written in...2004, one of the big takeaway points was that Perl 5 had reached a point where the limit had been reached as far as building on it and tweaking it and so forth. Having not plumbed the internals of Perl 5, I can only say the guy saying 'the internals of Perl 5 are a disaster' appears to know his topic really well.
So anyway if you'd like to try out Python 3.0 and like me are a MacOSX user, there's some immediate annoyance in your future. You've got to build the thing from source, not a terrible thing, but a DMG installer would be nice. Additionally, caution is necessary if you are just wanting to install alongside 2.x, as is the case unless you are completely mad. This article provides helpful guidance. It's all well and good, unless like me you have been just using the python that 'came with' and never went through the business of getting Darwinports installed, installing readline, and so on and so forth. After a bit of Googling, this article over on zopyx proved most helpful, and now I'm up and running.
In the event Google brought you here because of similar woes, now you should have what you need.