Responding to the rumors about a new NiGHTS game on the Wii, Yuji Naka, formerly the head of Sonic Team, told CVG that even if such a thing exists, he's not a part of it, and has no plans to be. Naka recently left Sega to form his own studio called PROPE, so for him to rejoin Sega for a project so soon would be slightly unusual.
The other major figure involved with NiGHTS is Naoto Oshima, who is now head of Artoon. If the two of them were to reunite to work on a NiGHTS game, then we'd really have something! But the fact that these two esteemed developers no longer work at Sega casts more doubt on the NiGHTS rumors, or at least makes them less exciting if true.