Many Exchange customers wants to move away from PSTs and take advantage of the expanded storage and compliance capabilities in the latest version of Exchange.
A new, free and downloadable tool called the "PST Capture tool" is (hopefully) entering (maybe private) beta soon.
With this tool you as an administrator will be able to scan repositories such as your network file shares to discover PST files, match the found PST files against your users mailboxes, and import data in the PSTs into the Exchange Store (Office 365 Exchange Online or On-Premises).
Note: the tool is not expected to convert (rewrite) X500 addresses to SMTP addresses - think of it more as a copy function as opposed to rewriting
Update Jan 30. 2012: the tool is now released and you can read all about it, see a video and download it here
Update Apr 29. 2013: Microsoft Exchange PST Capture 2.0 released in February 2013. Several improvements, most notably the UI is no longer limited to 1,000 users when performing an online import
Other improvements made in PST Capture 2.0 include:
See "PST Capture 2.0 is now available" for more