I use my iPhone to check my work email. It kills the battery but I've the BlackBerry as backup.
I'd love to be able to sync my calendars better. I use TripIt to update a Google Calendar with flight details. It would be ace to have that Calendar sync with my work one.
So, in theory you can now do this. Google walks us through the process here.
However, in all practical terms this is useless. You are only allowed one Microsoft Exchange account on the iPhone.
You can't use the same Microsoft Exchange account to sync your email and calendar.
In order to sync my calendar in this way I'd have to sacrifice having my work email on my iPhone. That's simply not going to happen.