I have finally launched a Planet feed aggregation at http://planet.profoss.eu. I say finally not because it was long and hard to set it up, but because I wonder how did not think of it earlier.
Included in the Planet are blogs and websites that cover professional open source.
Currently in english, I am interested in publishing planets in other languages, especially dutch and french.
If you want to be included, let me know (by mail or leave a comment here). The goal is to only include posts related to professional open source, and avoid any posts unrelated to that subject. It should be achieved easily with the help of tags and categories though.