I don't think it's a picatinny spec'd rail, but dawson precision makes one that bolts on to the 1911 dust cover. It requires a gunsmith or dawson precision to drill and tap the holes. It's the same rail istalled on the MARSOC Kimber.
The following link is for the rail and the surefire light.
Here is the link to DP for just the rail and surefire mount, it says that it will fit the Surefire P101, P111, or P217D.
Does anyone know if anything else will fit on this rail? Or is it made only for that Surefire mount?