HVY JET CREW ON VISUAL APCH INTO SFO RWY 28L RPTED AN NMAC WITH TFC ATTEMPTING TO MAKE AN APCH TO RWY 28R.

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PARALLEL VISUAL APCHS TO RWYS 28L&R WERE IN USE AT SFO. THERE WAS NO CLOUD COVER; AND VISIBILITY WAS GOOD; PROBABLY 15 MI OR BETTER. AT XA30 THE SUN WAS STILL FULLY ABOVE THE HORIZON; AND VISIBILITY TOWARDS THE SUN WAS SOMEWHAT REDUCED. OUR FLT WAS ESTABLISHED ON THE RWY 28L LOC AND GS ABOUT 3 MI FROM THE FAF AT AN ASSIGNED AIRSPD OF 170 KTS; CLRED FOR A VISUAL APCH; AND LNDG CLRNC WAS ISSUED BY THE TWR. WE HAD BEEN WATCHING A B757 APCHING OUR R SIDE FROM THE N. THIS B757 WAS ASSIGNED TO RWY 28R AND HAD BEEN POINTED OUT BY APCH CTL AS OUR PARALLEL TFC. IMMEDIATELY AFTER OUR CALL TO THE TWR APCHING THE FAF; IT WAS OBVIOUS THAT THE B757 WAS DRIFTING L OF THE CTRLINE OF RWY 28R. I ASKED THE TWR WHAT THE B757 WAS DOING; AND TWR REPLIED 'I DON'T KNOW; I'M NOT TALKING TO HIM.' WE WERE ABOUT TO BREAK OFF THE APCH WHEN WE OBSERVED THE NOSE COME UP ON THE B757 AS HE INITIATED A GAR. AT THIS POINT THE OTHER ACFT WAS JUST OFF OUR R WING. DURING HIS MISSED APCH; THE B757 DRIFTED FURTHER L AND PASSED A FEW HUNDRED FT OVER OUR COCKPIT; AND FLEW A MISSED APCH TRACK TO THE L OF THE RWY 28L CTRLINE. OUR ONLY EVASIVE MANEUVER WAS TO DSND SLIGHTLY BELOW THE GLIDE PATH MOMENTARILY. IT APPEARS LIKELY THAT ALTHOUGH WE WERE POINTED OUT TO THE B757 EARLIER BY APCH CTL; THE B757 DID NOT SEE US DURING THE LATER PHASE OF HIS APCH. THERE WERE SEVERAL CONTRIBUTING FACTORS TO THIS INCIDENT: THE SUN WAS LOW ON THE HORIZON TO THE W. ALTHOUGH WE COULD SEE THE ARPT CLRLY FROM 10-15 MI AWAY AND COULD SEE THE ACFT TO OUR R EASILY; HE MAY NOT HAVE BEEN ABLE TO SEE US IN THE SUN'S GLARE. ALSO; ALTHOUGH WE WERE CLRED FOR A VISUAL APCH; WE WERE ASSIGNED A SPD OF 170 KTS TO THE FAF; LIMITING OUR ABILITY TO SPACE OURSELVES A LITTLE AHEAD OR BEHIND THE OTHER TFC. AS A CONSEQUENCE; THE OTHER TFC ENDED UP DIRECTLY OFF OUR R WINGTIP. A LARGE CONTRIBUTING FACTOR WAS THE SPLIT FREQ ARRANGEMENT IN USE AT BAY TRACON. AT NO TIME DURING THE WHOLE EPISODE WERE THE 2 AIRPLANES INVOLVED ABLE TO SPEAK TO EACH OTHER OR TO THE SAME CTLR. THE B757 WAS WORKING THE N SIDE APCH FREQ; AND WE WERE INITIALLY ON THE S FREQ; AND LATER THE TWR. AS FAR AS I KNOW; THE B757 NEVER CHANGED TO TWR FREQ; AS HE HAD BEGUN HIS MISSED APCH JUST OUTSIDE OF THE FAF. CONSEQUENTLY; THE 2 ACFT WERE NEVER SPEAKING TO THE SAME ATC FACILITY OR SHARING A COMMON FREQ; EVEN THOUGH THEY WERE FLYING ONLY A FEW HUNDRED FT APART. LAST; THE B757 INITIATED A GAR BECAUSE HE GOT TOO CLOSE TO THE ACFT HE WAS FOLLOWING TO RWY 28R; NOT BECAUSE HE SAW US. HIGH COCKPIT WORKLOAD IN THE B757 COCKPIT MAY HAVE CONTRIBUTED TO HIS NOT SEEING US. IN SUMMARY; THE FOLLOWING CONDITIONS ALL CONTRIBUTED TO SETTING UP THIS NEAR MISS: 1) 2 ACFT VECTORED TOWARDS EACH OTHER WERE ON DIFFERENT FREQS; SPEAKING TO DIFFERENT FACILITIES. NO COORD WAS POSSIBLE. 2) SUN GLARE AT THAT TIME OF EVENING MAY HAVE MADE OBSERVING TFC TO THE L DIFFICULT OR IMPOSSIBLE. 3) ACCEPTING AN ASSIGNED AIRSPD UP TO THE FAF DEGRADED THE ABILITY OF OUR ACFT TO MANEUVER WHILE ON A VISUAL APCH. WE WERE ESSENTIALLY 'PUT IN THE SLOT' (LOC AND GS) AT AN ASSIGNED SPD BY APCH CTL WHILE STILL BEING EXPECTED TO MAINTAIN A SAFE SEPARATION FROM OTHER TFC. WHAT PARAMETER WERE WE PERMITTED TO CHANGE? 4) POSSIBLE HIGH WORKLOAD IN THE OTHER COCKPIT DUE TO PROX OF PRECEDING TFC TO HIS RWY. IT IS NOT KNOWN AT THIS TIME WHY THE B757 DRIFTED THROUGH THE RWY 28R CTRLINE; AND EVENTUALLY THROUGH THE RWY 28L CTRLINE AS WELL.