One can only hope that Washington has responded with an appropriate concession of its own. Since Iran evidently wants to keep this low-keyed, one would expect Washington professionals to behave accordingly, so we may not see any headlines. But what would constitute an appropriate response?
Not that I expect it, but to my mind, an invitation by Israel for the IAEA to inspect Dimona would have symbolic value (and anyone following the ridiculous issue of whether or not the Jewish Holicaust ever occurred is aware of the importance of symbols). An Israeli statement that they appreciate Iran's formal renunciation of nuclear arms and that the elimination of regional nuclear arms is also Israel's long-term goal would also be a nice move. A quiet berthing of Israeli nuclear-capable subs would be more appropriate, because Iran has made a concession of military significance and Israel needs to respond in kind. From the U.S., release of impounded Iranian funds would be an easy but noticeable gesture.
Update: This was a misguided U.S. response; one hopes there was more behind the scenes. Iran made a concession, but by itself, it does not seem to go far. The right to inspect Arak at will, without notice would be far more meaningful, but Iran took the first step and should be enticed to take another, not slapped in the face publicly. When will Obama learn to stop acting like Bush?
Technical Note: An IAEA slideshow states that an inspection agreement with a country:
Confers upon the Agency the right and obligation to ensure that safeguards will be applied on all nuclear material in all peaceful nuclear activities of the State.How convenient! It is the military application of nuclear controls that matters and therefore the military nuclear activities that need to be inspected. While the world gets itself all upset over the possibility of one Iranian bomb sometime, the steady buildup of Israel, Pakistani, and Indian bomb stockpiles gets a pass?!?