I gave apple the benefit of the doubt during the os4 betas, but now with the final OS out their activesync implementation is still broken. sending emails fails half the time, and even just syncing mailboxes breaks down if the mail app is left running in the background. i have to go into the multitasking bar and kill the mail app, then it starts synching again. the profile apple has produced to supposedly address the issue of their improper timeouts (which slam exchange servers) doesn't seem to resolve the issue. ugh!