C172 pilot entered the runway at an uncontrolled field only to hear an opposite direction aircraft declare himself on short final; the airborne pilot continued to landing.

Narrative

While taxiing from the FBO to the active Runway 16 I started talking to clearance delivery after I made my initial call to the field to let them know that I was taxiing. Clearance Delivery gave me a void time of XA:40 to be off and in the air; it was XA:38 at the time. At this point we called UNICOM and said we were taking the active Runway 16. The winds were at 230. As soon as we had crossed the hold short line a report came in from another pilot calling himself on base to Runway 34. I called back and told him we were already on the runway; but he replied and said I'll make this a short field landing and landed anyway. There wasn't enough room to turn around; and because I wasn't too far from the hold short line I just held at that point. After he had landed; I taxied the airplane off the runway and back taxied to pick up my clearance again. I believe some of the factors that made this happen was a rush to takeoff to get my void time and not possibly observing all the traffic in the area (however; neither myself nor the pilot in the other seat heard the pilot in the air call anything other than base). The other factor would be the pilot in the air not adjusting his flight plan and deciding to land even though we were on the runway. I believe if we had possibly waited a few seconds to listen to the radio after we made our call before taxiing onto the runway; we might have heard the pilot in the air's call before we taxied onto the runway.