OK, here's a quick note to those that are worried about limited data usage.
There is a setting under 'Accounts and Sync'. That allows you to turn off auto sync. Undo the checkmark and it will not automatically check the status on your accounts. You will have to refresh your email, or sync contacts, or check facebook on your own.
Within some applications there are settings for a refresh interval. For example - I have my weather widget set to a 3 hour refresh interval. I know that every three hours, it will update itself using a little of my data usage(that may be why you see usage while you are sleeping). Facebook, Gmail(or other email apps), Calender, and most weather widgets will update themselves on the schedule you have set up. Change the settings to manually update these, and there will be no automatic checks. (This is one time WinMob 7 will eat you alive - all those fancy homescreen widgets with automatic updates will chew up a limited data plan quickly)
This means you will not get your buddies latest post on facebook automatically, but it allows YOU to decide when to retrieve that info, and how much data you use at the time.
I have most of my apps set to a manual update (except for weather) and there is no data usage unless 'I' check for updates.