As far as I can tell, there are no formal US charges pending against Assange. There aren't likely to be any charges either, because he's done no more than the NY Times did with the Pentagon Papers. Unless, of course, the Justice Department wants to start indicting newspapers for publishing this sort of thing.
IANAL, but if Assange encouraged or guided Manning prior to her taking the documents then a conspiracy to commit espionage charge might be attempted. If a prosecutor wants to go after Assange I have no doubt they could find something to charge him; never underestimate the ability of a prosecutor to be inventive when interpreting the law and desires to go after someone. The morality of such an approach and whether or not those charges would stick or he would be convicted is another issue.