updated 10:20 pm EDT, Wed June 30, 2010
Update available as a configuration file
Apple has posted a fix for Exchange sync issues with iOS 4. Many users encountered problems attempting to sync with Exchange ActiveSync Mail, Contacts, or Calendars after updating to iOS 4. The issue reportedly caused a complete failure for some users, or an excessively slow sync for others.
The fix is available as a downloadable configuration profile that corrects the amount of time iOS 4 waits for the Exchange Server to respond to a sync request. The profile can be downloaded directly from the mobile version of Safari and directly loaded onto an iPhone or iPod touch.