Microsoft recently released a hotfix to enable Outlook 2007 clients the ability to access personal archives on Exchange Server 2010 servers.
Combined with the ability to move personal archives to a different mailbox store (in Exchange Server 2010 SP1) than the mailbox itself proves a really compelling solution for many organizations.
It may have taken a bit longer than expected, but the hotfix is now available.
Please. I beg you. Make sure you test the hotfix fully before you deploy it in production.
You should also keep a close eye on Knowledge Base Article 2485531. This KB is being used to track problems with the hotfix and workarounds.