There are indications that a new Pokemon title is on its way, as a website baring that title has been registered.
The company that registered the domain name - Melbourne IT DBS - also registered the Pokemon White / Black website for the DS twosome, giving the theory that Gray will be a remixed version of both titles some legitimacy.
While White and Black were released on the DS earlier this year, it'll be interesting to see if the release - if it is indeed a remixed version of the previous two, hits the DS or the 3DS.