After a phone call, the presidents released a joint statement, in which they promised to continue the work on the new treaty:

Joint Statement by the President of the United States of America and the President of the Russian Federation on the Expiration of the Strategic Arms Reduction Treaty (START)

Recognizing our mutual determination to support strategic stability between the United States of America and the Russian Federation, we express our commitment, as a matter of principle, to continue to work together in the spirit of the START Treaty following its expiration, as well as our firm intention to ensure that a new treaty on strategic arms enter into force at the earliest possible date.

In another statement the U.S. and Russian presidents recognized contribution of Belarus, Kazakhstan, and Ukraine. (The statements in Russian.)

This is quite discouraging. As I said earlier, I don't see why additional time would help resolve the differences if the pressure of a deadline did not. The only explanation that leaves some room for optimism is that the Obama administration was trying to protect itself from Republican attacks - had Obama signed the new treaty in time he would have opened himself to accusations of making unnecessary concessions to Russia. Now he can hope to avoid that (not that he will, though - the Republicans will find something to complain about anyway).

We'll see where we go from here. Optimists believe that the treaty will be signed on December 11th in Prague, pessimists consider a possibility of the negotiations dragging on beyond May 2010. I hope it's the former, but wouldn't rule the latter either.