Originally, it was suppose to be Diaz and not Condit in the title fight. Due to Diaz's inability to show up for a press conference, he was pulled and took Condit's spot against Penn.
But now, both fighters are looking for another shot at UFC gold. Diaz's for the above reasons, and Penn just for the fact that GSP has beaten him twice previously.
Not many people want to see GSP vs. Penn III, but it's going to be hard to keep both Penn and Fitch out of title shots forever.
Penn is 1-0-1 in his return to welterweight and has fought only the top fighters in the division. Penn has fought arguably the best welterweight the UFC has ever seen, Matt Hughes, and destroyed him in the first round in the first minute of the fight.
Then he came in and had an impressive first round against Fitch, but the next two rounds slowly but surely put Penn away and led to Fitch taking a draw from Penn.
Now Penn faces Diaz, yet another big name in his return to welterweight. Penn doesn't have so many fights left and is getting older. The people he has been fighting at welterweight show he definitely deserves a title shot if he gets past Diaz.
Now for Diaz.
Diaz originally had the title shot, and if he beats Penn, it solidifies his position not only as a Top-10 welterweight, but also proves he's deserving of another shot at GSP.
A win over Penn justifies that idea in a division that GSP has almost cleared out completely.