As of February 17, 2010, I have owned my 1150GS for one year.
The current mileage is 120,200, meaning I put 17,720 miles in the bike in the last 12 months. That includes having the bike out of commission for an entire month with the faulty Hall Sensor. So, based on 11 months, that's an average of 1,600 miles per month.
A 400 mile a week average is not bad when you live on a 2x4 mile island and have a 100 mile 2-lane road to the mainland.