If you installed Microsoft Office 2010 Beta as I did, you will find that it does not integrate well with Communicator 2007 R2 and the Live Meeting Add-in does not work either. To fix those problems, you need the following two updates:
Once you have the above two updates installed, you should be able to use Outlook 2010 Beta to schedule Live Meeting and Conference Call.
However, due to a confirmed integration error between OCO 2007 R2 and Outlook x64, you may get an Exchange Connection Error in Communicator like this:
I hope this error will be fixed soon.