Mozilla Labs has announced Mozilla Raindrop, "an exploration in messaging innovation", or a next-gen mail and messaging client.
I'm interested in this for a few reasons. First, it could someday be the way I read email, and goodness knows we could use better ways to deal with that mess. Second, it's built on Python and CouchDB.
On the down side, it's a rethinking of messaging, which is a quagmire where plenty of other enthusiastic innovators have lost their way before. Also, it's in the very early stages, and so has a long way to go before it's something people can use.
I'll be interested to follow its progress, both as a usable piece of software and as a showcase for favorite foundational technologies.