The list with Weaving , Oldman and other is definately a solid list for Moriarty IMO.
However if people want to actually see their choices in Holmes 2 instead of simply hoping their choices are chosen , i think that you guys need to consider the projects that are currently being offered to them.
Although we haven't got info from WB where they say "we want Holmes 2 in dec 2011 ", all signs point out that WB will go for that date again.
SO if you follow that date , HOlmes 2 might follow the same shooting schedule of the first movie. The first movie began shooting in oct of 2008 so there is a good chance of this movie also being shooting in oct. 2010.
Weaving might be still shooting Captain America when filming starts for Holmes.
Pitt's schedule on the hand seems to be pretty empty. He has movies lined up but not one is in active development currently. Ditto Irons who is my choice for Moriarty. The guy needs to have another juicy role IMO