Some time ago I met the people behind SmartGit (a cross platform git client) and they told me that using Google groups worked quite well for this purpose.
Google Groups suck as a forum. They flag valid comments as SPAM and miss good comments, they reject and delete posts for no reason and without traceability. They have no SEO value so they don't help product discoverability and to make matters worse they are really hard to search properly.
We still have it but try to focus on stackoverflow which is no panacea due to its own problems but at least it works properly.
Here's a link to their group so you can get an impression: https://groups.google.com/forum/#!forum/smartgit