If I understand this and this correctly, it means that Varnish now supports the Vary: header, which means that the last barrier to using this fast, easy-to-configure webserver proxy to front multi-lingual Plone sites should now be gone.

I also found a sample Plone/Zope config file for Varnish, contributed by Stig Sandbeck Mathisen. Cool!

According to Wichert, Plone.org is now using Varnish as its proxy.

Reading the tea leaves, it looks like a new generation of simpler, faster, easier-to-configure caching for Plone has arrived.  Hooray!

If you've had experience implementing Varnish for your Plone site, please share your stories.  I'm sure there are lots of folks who'd love to hear more.