Exchange team just released our Exchange 2010 SP1 information, read the details here http://msexchangeteam.com/archive/2010/04/07/454533.aspx
You will see that with SP1 we can now host the Archive mailbox on different database from the users primary mailbox which will help in case you want to host your archive mailbox on separate storage other than the one which is hosting your users primary mailboxes.
We also add the capability of importing emails from PST directly to the Exchange server and delegated access to the archive mailboxes.
Outlook Web App is loaded with new features and as they say “Better than ever”"…
New management UI and with EAS SP1 you can now send and receive IRM protected message without having previously connected your device to WMDC to enable IRM provisioning.
Jump to the link and read the details and for sure deploy SP1 once released….