I ran across this which was referred to by slashdot. The story basically discussed a sworn affidavit signed by the press officer at the military base in Roswell. Essentially, he confirmed that it was an alien ship that crashed and that alien bodies were recovered. He claims to have seen the ship and the bodies and that he was instructed to concoct the weather balloon story. Interestingly, the information only came to light after the person died since he forbid the affidavit to be released before his death.
This sounds to be the most concrete confirmation that a UFO did actually crash in Roswell. Of course, this is is also fodder for the conspiracy theory types.