WordPress.org has added a crowdsourced (beta) compatibility check for plugins. Every user can now report whether a plugin works with a certain (or upcoming) version of WordPress.
Above the results for the WordPress.com stats plugin and the 2.9 branch (pre-beta votes?).
Author: Franky Branckaute
Franky is CEO, Editor and 21/7 Muppet on Duty at Splashpress Media. Occasionally he even sleeps. More sporadically even he also blogs about the professional online life at iFranky. He also is regular Guest Lecturer on all things blogging and ‘web 2.0’ish’. Follow him on Twitter.