I have been searching for a while for an application that would let me sync my Outlook calendar at home, my Exchange calendar at work, my google calendar and my phone. Today I found Scheduleworld.com and I have to say that their service, which is FREE, is my silver bullet.
Using SyncML, ScheduleWorld.com has let me keep all of my calendars synced up.
Go check them out. http://www.ScheduleWorld.com