C206 pilot describes a miscommunication and conflict with airport vehicles during takeoff from Runway 7 at JHW.

Narrative

I was departing JHW. I announced via CTAF my taxi from the ramp to Runway 7. [I] arrived at Runway 7 hold short line as another aircraft announced position on a long final to Runway 7 via GPS approach. I announced to the incoming aircraft that I would hold short. I performed my engine run-up as the incoming aircraft executed a touch-go. I announced via CTAF 'departing Runway 7 Jamestown' and proceeded to taxi into position for departure Runway 7. As I taxied into position FAA Mobile announced via CTAF 'FAA mobile transiting to the ramp; crossing 7/25'. At that time I immediately requested via CTAF 'FAA Mobile advise when clear 7/25' FAA mobile did not respond. I again announced via CTAF 'departing Runway 7 Jamestown' and waited for a response. Two minutes later I began my takeoff roll. Approximately 1;500 FT down the runway I was 50-100 AGL and noticed two vehicles crossing Runway 7 well down the runway toward the 7/25-13/31 intersection. A minute later via CTAF 'FAA mobile clear 7/25' as I passed at approx 200-300 AGL the vehicles were on the taxi-way parallel to Runway 7 traveling toward the ramp.