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?
Communicator conversation history is enabled by an Outlook add-in. The current version of Communicator is 32 bit only. The add-in it ships with is 32 bit only. Unfortunately, that means it won't work on a 64 bit version of Outlook. Outlook 64-bit can only install 64-bit add-ins. It is for this reason that Microsoft recommends sticking with 32-bit versions of Office unless there is a need. The only big advantage of going 64-bit is to enable Excel spreadsheets over 2GB. If you don't have a need for this, why not install the 32-bit version of Office? It is supported on 64 bit machines.
The other option, unfortunately, is to wait and upgrade. Communicator 2010 should be out before too long and will likely include a 64-bit option.