You may be reimbursed by your company for the cost of your travel if flying
is incidental to the reason for the trip (meaning that the reason for the
trip could be accomplished if you drove or took a commercial airliner). You
may not volunteer to take people if you were not going anyway. This
reimbursement may take the form of a standard mileage rate or by computing
direct costs. You may not be reimbursed for your time when you are piloting
the airplane.

People will tell you that corporate attorneys, insurance, etc. will not
generally allow it. Actually, I know several people that fly their own
airplanes on company business. It is easier, of course, if you own the
company, but most of the people that I know are like sales people or
engineers for large corporations.