Come on, B3TA07... you can do better than THAT.
The Susan Boyle joke/reference was towards the end of episode where many people were auditioning to be a new cast member on the ficticious comedy show 30 ROCK is about. A reoccurring character, Kathy Geiss (the network owner's homely, plain Jane spinster middle-aged daughter -- played by actress Marceline Hugot) also auditions and sings "I Dreamed a Dream". Since she already has that Susan Boyle resemblance without even trying, the reference is quite hilarious.
Also, they end-up choosing a quite slim robot-mime street performer for the new cast member role, which is why some inquired if that was Cheyenne Jackson as its already been confirmed that he will be playing this role in the series. It was not Cheyenne Jackson -- it was actor Daniel Genalo who played the robot-mime.
Daniel Genalo: