There are a couple (Gingrich on Pelosi, for instance) but it doesn't seem to be the norm. Benedict XVI's profile, for instance, is written by Vittorio Messori, an Italian Catholic journalist who's pretty enthusiastic about his subject, and Tzipi Livni is written up by her good friend Condi Rice. I'm not going to go through the whole site now (I've just been to the optometrist and my pupils are still saucer-sized) but as far as I can tell, the choice of profilers is fairly haphazard.