We don't normally announce new Moodle modules here but this one is notable because it's one of the first GPLv2 software releases ever from Microsoft, so we're honoured!
http://www.educationlabs.com/projects/moodleproduct/
Their code (actually a block and an auth plugin) implements a nice integration with Microsoft Live services (allowing users to log in using their Live ID, as well as see and create emails and calendar events from within Moodle). Here's a video about it.
Since (from a programming point of view) Live has the same APIs as any Exchange server, I think a lot of Moodlers will be using this code to integrate Moodle closely with their private Exchange servers as well.
You can find out more about the code here in this blog post from L. Michael Golden.