I checked this list http://disarmament.un.org/UN_REGISTER.NSF and the lasted update by Iran was for 1998.
But, I agree with you the Russians have not yet supplied any S-300 to Iran.
In 2006 the Russians supplied India with 149 and China with 944 missiles according to the list above.
http://en.rian.ru/russia/20071228/94513968.html
As per usual the S-300/Iran issue continues. The above is the official reaction in regards to the Iranian announcement.
Any such sale will be officially announced by the Russians as per the Tor deal. The Russians have too much to lose in being found out once the S-300s show up in Iran.
The Iranians probably obtained bits and bobs of the S-300 system from such places as Kazakhstan after the break up of the Soviet Union. Having bits of the system doesn’t make it in anyway operational. Again, the associated radars are the give-away to this system. A system such as this requires to be exercised and tested. Iran can’t manipulate the electromagnetic spectrum. Even a TIN SHIELD early warning radar and associated to S-300 is going to attract the attention and cue imagery to have a look. Iran simply can’t operate such a system and not be found out. The Russians know this and that is why any sale, or even lease, will be officially announced.