It's all about the technique and the serving motion, doesn't really matter that he can smash an overhead with a lot of speed. He can serve above 200 km/h, we all saw it. Just not consistently. He still can't hit an above average second serve to save his life, but he's improving. His inside out (?) serve is much better then what it was, it's a real weapon now. I can recall at one point during the Wimbledon final they showed the statistic about unreturned serves, Roger had maybe 56-58, something like that, and Rafa had 51 or 53, and i think it was in the fourth, maybe fifth. Okay, Roger returning game was absolutely off, but still, Rafa is improving in this department. I think he and Tony will put in a lot of effort to keep improving it. I think we all lucky though that he don't have a special serve, imagine him with a "Samprasque" serve, that would be ugly.
I'm talking about "Golden Slam 2008 ugly" kind of thing.