The text of the Obama-Medvedev statement is now available. Actually, there are two of them: a long statement on life, the universe and everything and a short statement on strategic arms control.
The arms control statement is pretty vague; presumably it is intended to give the negotiators maximum flexibility (and fair enough). More interesting is the language on this point from the long statement:
As leaders of the two largest nuclear weapons states, we agreed to work together to fulfill our obligations under Article VI of the Treaty on Non-Proliferation of Nuclear Weapons (NPT) and demonstrate leadership in reducing the number of nuclear weapons in the world. We committed our two countries to achieving a nuclear free world, while recognizing that this long-term goal will require a new emphasis on arms control and conflict resolution measures, and their full implementation by all concerned nations.
Russians I had spoken to a couple of months ago thought that Medvedev would not be willing to mention a nuclear-weapon-free world (or even the ubiquitous but odd “nuclear free world”) and would instead insist on talking solely and more vaguely about fulfilling article VI. So, the wording used in the statement is perhaps noteworthy. A product maybe of the geronto-diplomacy we have seen recently?
Of course, the START follow-on treaty is most probably only going to contain modest cuts. Nonetheless, look at it this way: If, say, three years ago, you had been told that a young, liberal, black US President and his Russian counterpart had publicly committed their nations to the abolition of nuclear weapons on 1 April, what would you have concluded?