I'm on holidays in Far North Queensland (I got special permission from my wife to come to the internet cafe as long as I wasn't doing work - it's a good thing I love technology for technology's sake isn't it). I was wandering down the main drag in Port Douglas when I realised that my HP6315 had experienced a Hard Reset. Not a great situation as all of my holiday details were in there including car hire, accommodation, contact numbers and so on. However, after bringing the machine back up (and setting the date to the correct year!) I was able to connect to the Exchange Server in Singapore and re-sync 600 contacts, all my future appointments (and all of my email) just by filling in two bits of information - the server name (FQDN) and my domain credentials. 10-15 minutes of furious GPRS transfer later and bingo! I was back.
The really cool thing about this is not that I managed to hard reset the device (DUH), but if I'd lost the device (say, while on a cruise out to the Great Barrier Reef), re-provisioning a new one would have been just as easy.
BTW, this gets even easier with Exchange SP2 and the new Messaging and Security Feature Pack for Windows Mobile 5