My eye was caught yesterday by this article in the Guardian, describing the voyage into space (on the shuttle Atlantis) of some nematode worms from Bristol. Apparently some worms that were on board Columbia, when it broke up on re-entry in 2003 - the container which held them was discovered several weeks later.
According to the press pack for the mission (STS-129, which is also taking parts for the International Space Station), there are two experiments (known as CERISE). One will investigate the effect of microgravity on RNA interference, and the other (the one described in the Guardian) the effect of the space environment on protein phosphorylation and signal transduction in muscle fibres. A search of the NASA site (www.nasa.gov) for the word "nematode" will find some other experiments that have been carried out on C. elegans in space.
This mission is STS-129 and there is a launch blog here. There is lots more about C. elegans on the Caenorhabditis elegans WWW server maintained at the University of Texas Southwestern Medical Center in Dallas.
Later note : just discovered this NASA resource, "Ask a C. elegans expert", part of their Web of Life site.