Earlier this month we'd posted about an issue with Outlook 2007's support for Personal Archives, and that a fix has been checked in to the February 2011 Cumulative Update. The Office team has released the Office 2007 Cumulative Update for February 2011, which includes the Outlook 2007 hotfix. The update adds Personal Archives support in Outlook 2007. For more details about the hotfix, see KBA 2475891: Description of the Office Outlook 2007 hotfix package (Outlook-x-none.msp): February 22, 2011.
You can request the hotfix from here, or by clicking the 'View and request hotfix downloads' link in the KBA. You do not require the December 2010 Cumulative Update to install this update.