I was under the impression that American and Virgin are codeshare partners and that I would be earning AAdvantage miles on BOTH legs of the flight.
However, now that my ticket is purchased it appears that I am only earning miles for the American leg. Why is this?
Aren't American and Virgin codeshare partners? Was I mistaken?
(I realize Virgin isn't an official member of oneworld, but I thought they had some sort of alliance or something similar to being in oneworld....?)[/QUOTE]

No, AA is partners with BA - Virgin's primary commpetition, thus only AA miles for the JFK-LHR flight.