It seems pretty official now a source close to Meg Ryan says they have been dating for several weeks now and John and Elaine have been separated for awhile.

http://www.cnn.com/2011/SHOWBIZ/celebrity.news.gossip/01/04/meg.ryan.john.mellencamp.ppl/?hpt=Sbin

I worked as a reporter for a few years and, as a rule, I don't trust unnamed sources.

I believe they are just friends. They were probably just in New York working on the "Ghost Brothers" musical together.