Several people have asked, so I'm just making the announcement here so I don't have to keep answering the same question over and over:
Yes, Tim did audition for America's Got Talent this year. He was invited to audition by a lower-level producer, who scheduled a private audition time where he got to skip the long, all-day lines and where he got to audition by himself instead of in a group of 10-15 other singers.
They seemed to like it (but they've liked his stuff every year--he's made it quite far in the process over and over but never been on TV). They sent him on to the second audition of the day (a call back--a sign that he's not cut yet), and then to the interview segment (a sign he's not cut yet, still). The producers had nice things to say about his act.
And the audition ended with, "We'll call you--in March."
By the time they call, we will have forgotten what he auditioned for (and they said, "Remember what you're wearing, okay?" Really? For 6 months?).
So now you know everything I know.