Windows Phone 7 using lots of 3G data while idle, even on WiFi?

Complaints seem to be growing among some users that Windows Phone 7 is consuming an abnormally plump quantity of data when you're not doing anything. Granted, there's lots of stuff on the platform that might need data continuously -- email accounts and live tiles, for example -- but folks are reporting consumption measuring in multiple megabytes per hour, which can add up pretty quickly: 2MB per hour over a month is nearly 1.5GB, which can be a bummer for anyone with a 2GB data plan. The real issue, though, is that at least some of the data seems to be ignoring available WiFi networks and choosing 3G instead, so there's no great way to definitively avoid the leak even when you're in the comfortable confines of your own home. Our money -- our hopeful money, that is -- is on this being fixed in Microsoft's first big update that should be coming any day now, but in the meantime, users look to be getting at least some relief by setting mail accounts to manual update and turning off location services. Anyone out there seeing this?

[Thanks to everyone who sent this in]