Transmission site aggregator
The main transmission site (currently drupal) is aggregating news from projects in the network -- http://www.transmission.cc/aggregator
The news feeds from the aggregator itself is http://www.transmission.cc/aggregator/rss
The OPML feed is http://www.transmission.cc/aggregator/opml (currently not works)-- this shows a list of syndicatable feeds from all the projects
If you're an admin on the site - http://www.transmission.cc/admin/help/aggregator - is the help page for the aggregator.
The drupal documentation - 'Aggregator: syndicating content' is http://drupal.org/handbook/modules/aggregator/