I\'ve used Trac/Subversion before and really like the integration. My current project is using Mercurial for distributed development and it\'d be nice to be able to track issues
TracMercurial integrates Trac with Mercurial. Assembla provides free Mercurial hosting with Trac integration.
The idea is that you have a central repository as your master and upload all the subsidiary changes from local repositories into the main one.