According to Sergei’s biography page at Astronaut.ru (in Russian), he has reappeared on the ISS crew list, initially as a backup for ISS-21A (for cosmonaut Aleksandr Kaleri on the prime crew):
In 2008, Sergei has tentatively been named as part of the backup crew of ISS-21A. According to these plans, the prime crew will launch on Soyuz TMA-18 in March 2010. This will be the first flight of a new modification of the Soyuz-TMA spaceship (700 – Series 1).
