There are a whole bunch of "Working Group last calls" going on for email-related technology. Roughly, these are calls for reviews of Internet-Drafts before they are submitted to become standards. I called for reviews for an IMAP Extensions working group document which adds annotations (like properties, or metadata) to emails in an IMAP server. The Lemonade WG has issued last calls on these documents (all last calls on the mailing list and the documents themselves are linked from the Lemonade charter page):

• the Catenate proposal, used to allow clients to more efficiently work on draft messages stored on an IMAP server
• URLAUTH, which lets one user show an attachment to another user without sending them the whole attachment (basically I give you authorization to view my copy on my server)
• Server-to-server requirements for email event notification systems -- intended to allow voice mail and email servers from different vendors work together more smoothly
• The BURL draft, allowing clients to forward an email without downloading and uploading it again as email systems currently require.
  

There are also upcoming improvements to the performance and extensibility of the LIST command which is the heart of IMAP, and ongoing improvements to access control, both coming to a head in IMAPEXT. If you're interested in email protocol and developing standards for those, this is an exciting time for that. I guess that means about 7 of us globally are excited right now :)