rod perth?
I'm in the process of finally reading the book. I think the real Rod Perth (played by Ed Begley Jr in the movie) makes a cameo.
When Howard Stringer in the movie shows up to make the pitch to Letterman, he walks up to a guy and says "Rod?". He turns around, but it's not the fictional Rod Perth. Ed Begley is sitting down.
When the guy turns around, he looks exactly like Rod Perth's picture in the book. If that really is him, that's a neat way to do his cameo.