Until now Simple WordPress Framework, WordPress Plugin Framework and Xavisys Framework are the ones I found.
Xavisys is in use by http://xavisys.com/wordpress-plugins/efficient-related-posts/
Wordpress Plugin Framework is at http://code.google.com/p/wordpress-plugin-framework/
Simple WordPress Framework is at http://www.swpframework.com/
Any hints, ideias or directions for other frameworks are appreciated :)
