The 2010 Pro SL appears to be the same as the 2009 Pro SL, or at least uses the same 10r carbon material, whereas the SL2 used 11r. The 2009 Pro SL used the SL2 molds but with the lower carbon; I can't tell from the pics if this is still using the SL2 shape or if they are now using the SL3 shape but with the lower carbon.
The Specialized rep was in the bike shop yesterday and he said the Pro is the SL2. The only SL3 mold is the SWorks for the 2010 model year. They just use a lower carbon in this year's Pro vs. last years SWorks SL2.