After months of intensive discussion (more than a 1000 emails in dozens of threads spread over two mailing lists, and a couple of hundred additional private emails), PEP 435 has been accepted and Python will finally have an enumeration type in 3.4!
The discussion and decision process has been long and arduous, but eventually very positive. A collective brain is certainly better than any single one; the final proposal is better in a number of ways than the initial one, and the vast majority of Python core developers now feel good about it (give or take a couple of very minor issues).
I've been told enums have been debated on Python development lists for years. There's at least one earlier PEP (354) that's been discussed and rejected in 2005.
I think part of the success of the current attempt can be attributed to the advances in metaclasses that has been made in the past few releases (3.x). These advances allow very nice syntax of enum definitions that provides a lot of convenient features for free. I tried to find interesting examples of metaclasses in the standard library in 2011; Once the enum gets pushed I'll have a much better example :-)