Guys, it isn't "rumors". CNN says they have three different GOP sources confirming this. NBC, the AP, etc. have multiple sources. The Romney campaign is obviously watching all of this. If it wasn't Ryan, it would be kind of a humiliation for him, to have this many news outlets saying it's him, and then for Romney to pick someone else. The Romney campaign would have put out a statement correcting the record by now if it wasn't true.
Also the fact that it's going to be on the U.S.S. Wisconsin is a pretty obvious confirmation. You don't put Paul Ryan on your heavily publicized shortlist, pick a boat named after his home state, and then announce that it's someone else. Mitt Romney may be a heartless monster, but he wouldn't be that cruel.