Not to be outdone by Nick and Vanessa's very public NYE kiss [0], Jessica Simpson and John Mayer celebrated 2007 by "full-on making out" at the Hudson Hotel party thrown by Christina Aguilera. This is the first public acknowledgment of their relationship. Here's more [1]:

"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.'"

Well, whatever the story, we wonder if John helped Jessica get out of her holiday slump [1]. 2007 has to go better for her than 2006.

Source [2]