Pilot reports following G-IV into SSI Runway 4; calling downwind; base; and final on the CTAF. Another pilot called departing Runway 22; which did not register with the reporter until a NMAC occurs on short final.

Narrative

Prior to arrival at SSI; I was receiving VFR traffic advisories from Jacksonville Center. This was my first time into this airport. I canceled traffic advisories after I located a Gulfstream G-IV landing ahead of me at the airport. I called my positions at downwind; left base; and 1.5 (approx.) final to Runway 4 on the CTAF. I heard the G-IV on the radio ask; (I thought me) if I needed them to clear the runway just after I had turned final. At the same time as I heard the G-IV call; I saw it exit Runway 4. I did not respond to the G-IV as I was still some 1 mile away. A few moments later; I then heard on the CTAF an aircraft report departing Runway 22. As there was another runway at this airport; although I looked for the departing traffic on both runways; I didn't see any aircraft; other than the G-IV; which had exited the runway; and continued the approach. It didn't register that the aircraft was reporting its departure on 'my' runway in the opposite direction instead the other runway. As I crossed the airport fence I saw an aircraft about 50 FT to my left climbing out in a right turn. I called on the CTAF; 'Dude; What are you doing?' The aircraft replied that 'the wind was favoring 22.' I continued to land without having to turn. Although I had the 'right of way;' when I heard the aircraft report its departure; I should have repeated my call for final and aborted the landing if contact could not be made with the departing aircraft.