Open Source Community Platforms

For some reason, last week was the week of open-source community platforms for me. The topic just kept coming up again and again. Of course, I have a soft spot for open source. The first web server my team ever built circa 1995 was on Linux and Apache. It was easy and accessible, and because of that, it was powerful.

Here are a few of the platforms that have been on my mind of late. I'd love to hear more from folks with experience on any of these or other platforms.

Facebook
The big news of last week was the opening of the Facebook API.
http://developers.facebook.com/

Pringo
I spoke with these guys last week. Their product is compelling.
http://www.pringo.com

Drupal
I had lunch with a colleague who runs a community at a large non-profit, and their site is built on Drupal. She had great things to say.
http://drupal.org/