For real time communication about anything semi-related to Synfig, feel free to drop by #synfig on the irc.freenode.net IRC network. If you have questions, comments, or just want to say hello, feel free to drop by!
If you are using Jabber, give #email@example.com a try.
There are some forums at http://synfig.org/forums/ for people who prefer forums.
There are also 2 email lists - one for users and one for developers for those who prefer email: