Well the article, if it says they never signed, is wrong. Russia and the US *did* sign it. In fact it was signed in London, Moscow, and Washington DC on January 27, 1967. Of course, I scanned of the article for the relative text that says we didn't sign and can't find it, so I don't know where you got that from, Invictus.
"On June 16, 1966, both the United States and the Soviet Union submitted draft treaties. The U.S. draft dealt only with celestial bodies; the Soviet draft covered the whole outer space environment. The United States accepted the Soviet position on the scope of the Treaty, and by September agreement had been reached in discussions at Geneva on most Treaty provisions. Differences on the few remaining issues -- chiefly involving access to facilities on celestial bodies, reporting on space activities, and the use of military equipment and personnel in space exploration -- were satisfactorily resolved in private consultations during the General Assembly session by December.
On the 19th of that month the General Assembly approved by acclamation a resolution commending the Treaty. It was opened for signature at Washington, London, and Moscow on January 27, 1967. On April 25 the Senate gave unanimous consent to its ratification, and the Treaty entered into force on October 10, 1967."
from: http://www.state.gov/t/isn/5181.htm