Si cranksets are double-only.
I suppose I should expand upon my earlier answer...if the question pertains to specifically whether the chainrings are optimized for shifting with either Campy or Shimano (or SRAM, for that matter), the answer is that there is no issue there. As far as the cranksets go, the Si cranksets are set up with a 43.5 mm chainline which should work fine with either system. Their chainring designer said the crankset system works well with either of the two major players, though he was partial to Campy as a personal preference alone. Bolt circles are 130 mm for standard chainrings or 110 for their compact chainrings, each on a five bolt circle. This, of course, excludes the Zipp crankset we are making for them, which is on a 4-bolt 110 mm BCD and will work well for any of the major players in the drivetrain market.