Varnish for Joomla 3.2 will be released next week. The plan was to release it this week, but Joomla 3.2 increased its dependence on sessions and the patch can not operate the same way it did before.
In previous versions, we did what we could to not even create sessions in the database, thus lowering the number of disk writes required to serve users' requests. Unfortunately it doesn't look like it's possible any more and the best we can do is not sending session cookies to the user.
This is a new approach and while it passes all internal tests against a vanilla Joomla install, it needs more testing with supported 3rd party components.
I'm sorry for the delay, we got many requests about 3.2 availability in the past two weeks.