Known Issues (as of v0.53)

• Re-occurring events are synchronized as their individual events (so you can't see the fact that they're repeating in iCal)
• Task reminders are not mapped to alarms in iCal.
• A new calendar is created in iCal for syncing (this means you can't pick to sync a specific calendar, say the entourage calendar)
• Contact birthdays will some times cause a conflict even though it says both Address Book and SF3 have the same value.
• The sync will fail if any of the FieldMappings fields are hidden in Salesforce.com to your user profile (typically via Field Level Security)