As you may have heard/read, Exchange 2010 Personal Archive support is now available in Outlook 2007 as part of the Office 2007 Cumulative Update for February 2011. The Microsoft Exchange Team Blog post Yes Virginia, there is Exchange 2010 archive support in Outlook 2007 covers how Personal Archive works in Outlook 2007. It is also detailed in the updated Exchange Help article Understanding Personal Archives.
Personal Archive is a feature available with Microsoft Exchange Server 2010 Messaging Records Management (MRM). It can eliminate the need for Personal Folder files (.pst). By using Personal Archive in Exchange Server 2010, the e-mail archive folders are stored online so that users can access the archived files by using Microsoft Outlook Web App or from a secondary computer by using Outlook 2010 or, now, Outlook 2007. By using any of these client applications, users can view an archive mailbox and move or copy messages between their primary mailboxes and the archive.
You’ll want to check out the Exchange team’s blog post and article Understanding Personal Archives to see how the functionality differs between Outlook 2007 and Outlook 2010. Of note, in Outlook 2007, you cannot search across the primary and archive mailboxes. Also, in Outlook 2007, a user cannot use personal tags (also known as archive policies) to move items to the archive mailbox. However, default archive policies will continue to be applied. Users can use Outlook Web App to see or apply archive policies.
Happy archiving with Exchange Server 2010!