I don't have problems with OWA, works normally, we use both form-based authentication (higher security for external use/webmail) AND Integrated authentication (for internal use, sharepoint integration).
But it might be that we have a problem with delegates accepting meeting requests. After rollup package 8 it seems that an appointment, will stay tentative after the delegate accepted the meeting request e-mail. When you open the user mailbox calendar and view the details of the appointment, you can see that the delegate accepted but it remains tentative, also after some time of waiting (> 2 hours, no change).
The delegate is has publishing editor permissions on the Calendar.....
Does anybody also have noticed this behavior? The user has an iPhone which he uses to synchronize with exchange...(read something about problems with blackberry devices and delegates accepting problems...)