I understand Ben Stiller, Owen Wilson, and Chris Rock, but I'm not entirely sure of Jack Black. The formers have a pretty diverse or good background in acting and producing, but Jack Black hasn't really proven himself compared to the others. IMHO, he should have been replaced with Will Ferrell, who not only writes and stars in very, very funny and profitable films but is branching out in drama.
And what about Borat/Sacha Baron Cohen? He was the talk of the town last
year.
... Just my two cents... Doesn't matter all that much, since they will feature them on the cover but write only one or two paragraphs about them in the end...