There's a very interesting BBC report, by Jonathan Amos, detailing the decision facing ESA in allocating funding for the space missions for the next decade.

http://www.bbc.co.uk/blogs/thereporters/jonathanamos/2011/02/european-space-prepares-to-mak.shtml

The biggest decision European space scientists have faced in almost two decades is which big missions they can afford to fund. They have to choose a project that will do something extraordinary, both scientifically and technologically. The European Space Agency has just announced the final three missions, which will be considered for joint funding with other space agencies such as NASA.