I've come up with a Linux kernel-like system where 3.1.x is retconned into the 'development' branch. Hopefully sometime on this vacation I'll decide to finish the 'development' work and release a Beautiful Soup version 4 that everyone can use.
Here's the direct download. Mon Nov 30 2009 23:08 Beautiful Soup 3.0.8:
I bet you didn't expect a Beautiful Soup release (unless you saw the foreshadowing a couple days earlier). But Aaron DeVore made a bunch of improvements, and 3.0.x is still the branch you'd use if you had a choice, and I decided to spend a few hours applying patches and writing unit tests, and there you go.