wpdevel follows what gets committed into WordPress core. This may be easier (and less cluttered) than the wp-svn mailing list (except for the occasional Twitter downtime that is:)
WordPress Plugin Coding Tips
Stephen, on his geek blog Nerdaphernalia, is running a series of excellent posts giving advices to plugin authors for neat subtle effects: adding a "Configure" link right next to the "Activate" link on the Plugins page, or how to give credit to your plugin without cluttering the page (I'm a big fan of the "Configure" link trick, that I've added…