I'd plop this one directly in the rumour box, assuming such a box exists, but we've heard reports that Activision is currently using surveys to gauge the level of consumer interest in a Call of Duty iOS or Facebook game.
A questionnaire currently being run by YouGov, which often initiates consumer surveys, has been floating around, asking questions like 'would you be interested in a Call of Duty Facebook game' or Would you like to play a Call of Duty iOS game'.
This is absolutely to be taken with a pinch of salt for a couple of reasons -- first, Activision would be crazy if it wasn't at least considering iOS or Facebook Call of Duty games and, second, it's just a survey.
That said, it is interesting. Activision has been a bit of a slow starter in the digital realm and has preferred to reap the rewards of full price, retail titles based on their multiple franchises. If Activision was to finally make a move into that realm it would make sense to do so with one of its mega franchises, like Call of Duty.