It looks like the United States is serious about keeping open the option of extending the START Treaty - answering a question at a press-briefing, the State Department spokesman said that the United States and Russia would meet in November at a formal meeting required by the treaty. This is the exchange:
Question: Has a meeting been scheduled between the U.S. and Russia regarding anti-missile treaties? If so, when is the meeting scheduled? Who will be attending? What will be discussed?
Answer: The U.S. and Russia have held extensive discussions regarding a Post Strategic Arms Reduction Treaty (START) agreement and we expect to continue those discussions.
With regard to the extension of a START, the parties are obligated to meet no later than one year prior to the expiration date of the Treaty, i.e. December 5, 2008, to begin consideration of whether or not to extend the Treaty. The Parties to a START will meet in Geneva in mid November to initiate this process.
I haven't seen anything from the Russian side yet, but there is no reason for Russia to not show up. I guess Ukraine, Belarus, and Kazakhstan would have to be there as well - they are formally parties of the treaty. I hope that eventually everyone would realize that the easiest thing to do would be to extend the treaty for five more years without any changes.