That's right--Weird Al had a cameo, again. Unfortunately, it was a cameo in the truest sense of the word, being all too brief. Homer invented grunge music, you see (it was a flashback episode), and Weird Al parodied his song. Amusingly, the fake parody was totally lame and nonsensical and involved food in some fashion--it was a parody of Al's parody. Well played, The Simpsons, well played.
I also feel I should note how good a sport Weird Al is for singing the bad song.
Possibly the best thing about Weird Al's cameo came after his cartoon form had left the screen. Homer, all depressed (which is why he invented grunge music, of course), not even cheered up by the parody, muses on his lowly state, acknowledging, "He who is tired of Weird Al is tired of life." How true.
The good line leads me to the most surprising thing about the episode--it was actually good. I don't know how long it's been since I've seen a first-run Simpsons that I've enjoyed, but safe to say? A long time. I mean, there was single, cohesive plot; the jokes were funny instead of lazy and random; and it was character-driven instead of cram-every-one-note-bit-character-in-there . . . driven. I was so pleasantly surprised that I even watched the episode that came on after the Weird Al one, and discovered that it was pretty good, too. It had the latter-day-Simpsons banes of the totally unrelated B-plot and of "Homer makes up a song! Because he's always done that all the time! Remember?!?" However, the B-plot was introduced in minute 2 instead of minute 15, unlike many newer episodes I've seen, and the "Homer sings!" was . . . not as annoying as it could have been.
In short, the good news is A: The Simpsons has apparently turned a corner, back toward being halfway decent television and B: Weird Al continues to ROCK MY FACE OFF.