Matt Wald,
I realize that you consultants would get shot for this type of time accounting, but what about you corporate hacks? Do you treat travel time as "work"?
When I was a consultant, the answer was definitely YES, and I was expected to bill the client for it (assuming it was a time & expenses contract, as opposed to fixed fee). Granted, I usually worked on the plane (planning for the meeting, or getting started on the ubiquitous follow-up), which made me even more feel it was reasonable to count (and bill) the travel time.