The agreement was signed on May 6, 2008 (follow this link for the text of the agreement and accompanying documents). The Bush administration submitted it to the Congress on May 13, 2008, but withdrew the document in September 2008.
U.S.-Russian 123 agreement on nuclear cooperation passes U.S. Congress
The U.S.-Russian Agreement for Cooperation in the Field of Peaceful Uses of Nuclear Energy, also known as an 123 Agreement, passed the approval procedure at the U.S. Congress. The agreement did not require an explicit approval of the legislators - it is approved the Congress doesn't take an action against the agreement during 90 days of continuous session (see CRS report on the issue). The agreement was submitted to the Congress on May 10, 2010 and the 90 days period ended on 8 December 2010. The Russian Foreign Ministry in its December 9, 2010 statement welcomed the approval of the document.