Since upgrading from Office 2007 to Office 2010 (x64), conversation history from Office Communicator 2007 R2 no longer is saved into Outlook's Conversation History folder, even though Communicator states that a conversation was saved.
There was talk of this being an issue during the betas, and even some afterwards, but I've never really seen anybody say that there was a fix for this.
Has anybody come up with a way to configure Outlook (x64)/Office Communicator to work together?