Wow, no screwing around by the bookies anymore.
Normally Nadal vs. Federer on clay has Nadal paying something around 1.50, with Federer 2.30 or so.
They've finally caught on, and Nadal has started at 1.28. I expect some money to come on Federer soon, who is currently paying 3.75 (wow!).
Federer in 2005 (semis), and the 2006 and 2007 finals was playing better tennis in general than he is this year yet never looked like beating Nadal (3 sets, 4 sets and 4 sets). Whilst Nadal is only getting better and better (look at how he's absolutely dominated his opponents this year - Niemenen, Verdasco, Almagro and a fairly comfortable win vs. Djokovic bar the 3rd set where he was a double break up but it went to a tie-break).
Federer has also dropped sets to opponents he shouldn't have. Fair enough Monfils (who pushed Federer) and Gonzalez, but Montanes?
I just cannot see Federer doing it. It'd be immense though, and if he does it, it'll completely break the trend and will be simply due to mental strength, and the awe of the occasion.
Mind you, obviously far stranger things have happened in sport.