B737-300 CREW AND A LIGHT COMMUTER ACFT HAD QUESTIONABLE SEPARATION WHILE ON APCHS TO RWYS 27R AND 35 AT PHL. THE ATCT LCL CTLR DID NOT ADVISE THE CREW THAT AN ACFT; LNDG ON RWY 35 WOULD PASS IN FRONT OF THEM.

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NOT REALLY AN 'INCIDENT' AS SUCH; BUT IT DID GET OUR ATTN BIG TIME. THEY WERE USING W RWYS AND ON SHORT FINAL TO RWY 27R THEY HAD A COMMUTER CROSS OUR APCH PATH LNDG ON THE CROSS; N RWY. (HE CROSSED OUR FLT PATH FROM L TO R.) WE WERE NOT TOLD ABOUT THE OTHER TFC UNTIL I ASKED. TOOK MOST OF OUR ATTN AWAY FROM THE FLYING DUTIES OF LNDG. FOR QUITE AWHILE; THERE APPEARED TO BE A 'CONSTANT BEARING' BTWN HIM AND US WHICH MADE US A BIT APPREHENSIVE. THE COMMUTER ACTUALLY CROSSED OUR PATH WHEN WE WERE APPROX 300 FT ALT. I CONSIDERED IT VERY UNUSUAL; IF NOT DANGEROUS (AGAIN; IT WAS SO UNUSUAL; THAT IT TOOK A LOT OF ATTN AWAY FROM THE APCH AND LNDG ON OUR ACFT). I HAVE NEVER SEEN ANYTHING LIKE IT IN MY CAREER. I CALLED THE TWR AND GOT A KIND OF 'SNIPPY' ANSWER THAT BASICALLY SAID THAT THEY WERE AUTH TO DO IT; IT WAS LEGAL; AND IT WAS A 'CLEAN' MANEUVER. I ASKED TO TALK TO THE SUPVR AND BASICALLY GOT THE SAME ANSWER; THOUGH NOT AS 'SNIPPY.' SUPVR SAID ZZZ IS FIRST ARPT AUTH TO USE THIS NEW PROC AND IT IS EXPECTED TO BE USED AT OTHER ARPTS IN THE FUTURE. IF THIS IS SO; WHY HAVEN'T WE (THE AVERAGE LINE PLT) HEARD OF IT? A FEW QUESTIONS COME TO MIND. WHAT IS THE CRITERIA FOR USING IT? HOW CAN I BE SURE THAT THE SEPARATION IS ADEQUATE? WHAT DO WE DO IF WE HAVE TO DO A GAR? ARE THERE WELL THOUGHT OUT PROVISIONS IF BOTH OF US HAVE TO DO A GAR? WHAT ARE THE WX MINIMUMS? WAS PLT'S ASSOCIATION INVOLVED IN THE CONSTRUCTION AND AUTH OF THIS PROC? CAN WE AS PLTS REFUSE IT (LIKE LAHSO)? IF SO; WHEN DO THEY TELL US THE PROC IS IN EFFECT (ATIS; APCH CTL; SHORT FINAL; NEVER)? ARE THEY STILL REQUIRED TO POINT OUT THE TFC AND LET US KNOW WHAT IS GOING ON? WHAT IS THE PROC CALLED? CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE CAPT CALLED THE TWR TO DISCUSS THE HANDLING OF HIS FLT. HE CONSIDERED THE LIGHT COMMUTER MUCH TOO CLOSE. IT DID NOT GIVE HIS ACFT ANY WAY TO GO AROUND. THE RPTR SAID THE DISTR CAUSED THE CREW TO GET A GPWS WARNING 'LOW GS.' HE WAS NOT HAPPY WITH THE RESPONSE TO HIS COMPLAINT. HE CONSIDERS THIS A DANGEROUS CTLR ACTIVITY TO CLR ACFT TO LAND ON RWYS 27 IN CONFLICT WITH ACFT LNDG ON RWY 35.