Using Outlook 2003 and Exchange 2003
When scheduling meetings to occur after July 1, 2008 there is no free/busy information available for any user. We can see the free busy information for the resources (conference rooms, etc) but not users. There is information available up to midnight of June 30, 2008.
At first I assumed users were not publishing their data far enough in advance, but I've found they are set to 12 months. We have run the /cleanfreebusy switch when launching Outlook but that doesn't seem to help. (There is no error message)