This time the expedition commander is a Russian, Genady Padalka, with his American Flight Engineer Michael Barratt. The custom is to switch nationalities of the commanders every mission. Michael Fincke was the commander of Expedition 18. He will be returning when the crews make the official change.
Along for the ride this time is space participant Charles Simonyi, making his second space tourist flight to the ISS. I can't recall for sure, but I believe he's paying about $30 million for this privilege. He will return with the Expedition 18 crew.
Staying on the station today is Japanese astronaut Koichi Wakata, who becomes another Flight Engineer crew member for the Expedition 19 crew. He arrived with the STS-119 mission last week.
The Soyuz docking will occur on Saturday.