The hot topic of immigration has been dealt with in a number of shows. But I distinctly remember the one from HIMYM, where Robin faces deportation to Canada and must get another job in something like 2 weeks or so.
Nevertheless, this was an excellent episode. Usually the ones where Raj is made the central character, the episode generally doesn't invoke that many laughs. Here, a new chemistry using Raj and Sheldon is experimented and the result is 30 minutes of top class comedy. Kunal Nayyar has evolved really well from a sidekick actor to one who can make or break an episode with his lines. The parallel track involving Leonard, Wolowitz, and Penny could be noted as a low point in this episode. Except for the SATC joke, which was hilarious.
Nice going BBT.