I was watching NY1 (the local news channel) and I heard absolutely NOTHING about radiological materials on board the plane. Thank God!
They suspended all traffic on Runway 31R and everything has been proceeded to used Runways 31L and 4RL.
My guess is that Russians discovered that some mafia type (they Russian mob is HUGE over here) was heading over the NY and wanted to get him back. I think they have to worry about that situation in Moscow with the theater! Now that's scary!