B777 at 800 FT and assigned Runway 28R SFO described a conflict event with a light jet when ATC initiated a last minute runway change resulting in the light jet directly overhead; the reporter noting this was becoming standard at SFO.

Narrative

We were on right base to Runway 28R with 180 KTS assigned speed and instructed to follow an Airbus on final to 28R that we now had in sight. On the dogleg base leg we were instructed to reduce speed to 160 KTS and then 150 KTS because they placed us only 3.5-4 miles behind the Airbus. We were told that there is a Citation Jet on final to 28L behind us that had us in sight. At no time did we report that aircraft in sight; nor were we asked to do so. The Citation was to follow us. Inside the San Mateo bridge; and having reduced to final speed of 140 KTS and fully configured; we were told to switch runways to 28L and that the Citation behind us would be switched to 28R. We were at around 800 FT on final to 28L fully established and configured. I noticed that there was TCAS traffic almost directly above us and slightly behind us. Shortly thereafter we received a TCAS RA. Upon landing we were instructed to telephone the Tower. We spoke with the Supervisor who asked us if we were filing a NMAC report. We said we would only file a company report. The Supervisor said that SFO Tower and the Citation had no issues. I thought they would actually apologize. This was very poor handling from SFO ATC for placing us so close to the Airbus and placing a light jet so close behind us. The TCAS target was so close behind us; that the actual TCAS depiction showed him practically directly above us with almost no lateral separation. Unfortunately this has become standard procedure at SFO.