Verizon HTC Rezound, ICS 4.0.3.
This seems to be a common problem, especially with ICS, but I have yet to find a definitive solution that works for me.
I just got my new phone, and have gone through the basic setup including syncing the phone to my workplace Exchange account. Mail's fine (up and down), contacts are fine (down at least, not sure about up), and events created on my phone are pushed up to the server and then to my office desktop, but events already on the server do not sync down to the phone.
I found one potential solution for another HTC ICS device; delete all Calendar-based data and then remove and reinstall the Exchange account. Did that, still not working. My last phone was relatively ancient (Sony XPeria X10, Android Eclair), used TouchDown for its mail program, and had a number of problems, but appointment synchronization wasn't one of them. What's the deal?