According to a recent conversation on Usenet (which may not be legally binding) you could conceivably claim this mileage reimbursement towards rental of an airplane (or towards costs on your own plane) if you traveled somewhere and wanted to build some hours while at it. The trick to it would be that the flying must not be a requirement, eg, it must not be needed for your job or else you fall into the 'paid to fly' complications that require a commercial certificate, different insurance, etc etc.