I bought a 638 day after Christmas (which had a cylinder problem, so it got shipped to them and the cyl was replaced), and dropped the rebate in the mail the weekend following my purchase. My dad bought his S&W a month or so before mine, and has still not received his rebate. My gun got there, was repaired, and got back already.
Methinks they just kinda have their hands full. They were off/closed for like a week around Christmastime, so they're probably just starting to get over their backlog of stuff to do. Nov. and Dec. were crazy-busy firearms months, after all.