this is the way a cameo is supposed to work in a movie- where the guest star is funny, but adds to the movie instead of taking it over (see, or rather don't see "Mars Attacks" for example of bad cameos at work). Mr. Steve Martin works well with Kermit and Piggy.
I wanted to show a clip from his appearance on "The Muppet Show" but the guy who uploaded it to Youtube won't allow embedding of his copywritten material. can you believe that? and it featured FUNNY BALLOON ANIMALS!