Today I have office walked 1000 miles between 10/13/2008 and 8/14/2009! The last 200 miles or so have been on my new Vibram Five Fingers. I now walk between 1.5-2.0 miles an hour at an incline of 1 (almost) all day at work (my desk is over a treadmill, see post linked earlier).
Here is my walking log.
(The Proclaimers - I'm Going To Be (500 Miles)) * 2