Actually, the rates for transportation workers is better than the standard GSA rate of $39.
from irs.gov - pub 17 chap 26
Special rate for transportation workers. You can use a special standard meal allowance if you work in the transportation industry. You are in the transportation industry if your work:
Directly involves moving people or goods by airplane, barge, bus, ship, train, or truck, and
Regularly requires you to travel away from home and, during any single trip, usually involves travel to areas eligible for different standard meal allowance rates.
If this applies to you, you can claim a standard meal allowance of $52 a day ($58 for travel outside the continental United States) from January 1 through December 31, 2006.
Using the special rate for transportation workers eliminates the need for you to determine the standard meal allowance for every area where you stop for sleep or rest. If you choose to use the special rate for any trip, you must use the special rate (and not use the regular standard meal allowance rates) for all trips you take that year.
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There's a lot of stuff to look at if you're doing your own taxes. Pub 17 has a lot of info. I'm not a tax specialist, but I'm going to try to figure it out on my own this year.