Space Shuttle Discovery is currently docked, and all 10 astronauts currently on the station (from the US, Russia and Japan) passed a microphone around to speak about life in space, some of their experiments, and plans for future ISS crews.
Favorite sound bytes:
"Members of Congress are big kids when it comes to talking to astronauts."
"Do you guys still drink Tang up there?"
"How many stars are there in space?"
President & Pals - ISS Crew Videoconference
There’s a marvelous photograph gallery on Yahoo! showing both ends of the call, Discovery’s recent take-off (STS-119), the trials & triumphs of recent spacewalks, the Canadian robot arm, the newest set of solar arrays and other modules of the almost-completed orbiting station.
The NASA web site has both audio and a transcript of the call -- and they mentioned it was the fifth presidental communication. The other four were Lyndon B. Johnson (1965 Gemini call), Richard Nixon (1969 Apollo 11 call), Ronald Reagan (1981 Shuttle call) and George W. Bush (2006 ISS call). Obama was the first to include a crowd for educational and inspirational purposes :)