Seriously, I hear a lot about web use and Facebook but what about other things. Do those with high usage use the auto-upload for Skydrive? Is "find my phone" turned on, and if so is it set to periodic or all the time? What about "feedback," is it on or off, and is it set to be allowed to use your cellular data plan? These are all options on the phone, and they are options that could quickly rack up usage if forgotten about. My WP7 phone has quickly become my camera of choice for point and click exactly because it auto-uploads to Skydrive. I was not amazed at all when I had used 1 gigabyte of data with my new WP7 phone the first month I had it.