Deploying Topol-M with more than one warhead has often been mentioned as an option that Russia can choose in response to U.S. missile defense system. Right now, MIRVing of Topol-M is prohibited by the START treaty, but the treaty will expire after 2009. Will Russia choose to deploy multiple warheads on its Topol-M missiles?
Probably not. Although development of a MIRV warhead for Topol-M seems to be technically possible, if Russia decides in 2009 that it needs MIRVed missiles (a fairly big if in my view), it will probably choose to deploy the Bulava missile in this role.
Bulava from the very beginning was marketed by its developer, MITT, as a universal missile, which can be deployed on land as well as at sea. This point was recently underscored by the defense minister and the president himself, so it seems that the missile will have this capability from the very beginning. Besides, adapting an SLBM for land-based silo basing should not be difficult at all (unlike trying to deploy land-based missile on a submarine).
No details about Bulava have been released so far, but it seems extremely unlikely that a missile deployed on submarines will carry one warhead. It is almost certain to be MIRVed, so if Russia wants to deploy a new MIRVed missile in silos on land, it will not have to go an extra mile and develop a new warhead for Topol-M - it will have Bulava.