I use "TouchDown for Android" (email app). It works great and syncs everything. Not sure it actually uses the phone's calendar, as it has its own -- sort of like Outlook does.
The bad news is that it's usually $20, which is steep for an app these days, but I found it well worth it, as this is the primary reason for my smartphone.
The other bad news is that the market only gives you like 15min to return an app if you don't like it.
The good news is that you can d/l Touchdown and configure it and try it out for free (I forget the restrictions on it -- it might insert a "Sent with TouchDown" signature in all your emails or something during the trial). The better news is that it's 1/2 price today if you buy it from the Amazon App Store.
All that said, I think the Gingerbread sync is able to work with Exchange Server and the calendar, but I could be wrong...