I saw it Saturday night and it ran about 2:50. I don't know if the show's frozen yet (after all, they do still have 2+ more weeks of previews), but I definitely don't see it getting longer than that or much shorter, either.
Thanks. Kind of funny, before posting I was searching the Shuffle Along preview thread without success on runtime, but just after I posted, I saw Alex10 had just posted last night's runtime! 2:50 it is -- or close.