Jessica Simpson and John Mayer were 'full-on making out' at the Hudson Hotel in NYC on NYE!

John Mayer and Jessica Simpson rang in '07 "full-on making out" at the Hudson Hotel party thrown by Christina Aguilera. It was the first public acknowledgment of a relationship they have been denying since August. (The mystery source on that first story, by the way, was a deliveryman who saw Mayer in his boxer shorts at Simpson's home, and sold it to the tabs.)

"He was scratching her back, they were kissing, it wasn't subtle," says a spy at the Heineken-sponsored bash. The couple dined earlier in the evening at Country, after shopping at Barneys during the day. A source tells us they are staying together at The Mercer hotel in SoHo. An insider says: "John has been thrilled that they have been tricking the media, but she doesn't really care. His Christmas present to her was a framed copy of the Us Weekly cover that says 'Dumped: John ditches Jessica.'"

By the way, John, you might want to have a word with your posse: That party guest your friend asked about buying drugs was a Daily News Reporter.

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