(Image source: MovieNet News)
It has been confirmed that Simon and Nick have been cast to play Thompson and Thomson in Steven Spielberg and Peter Jackson's feature adaptation of Tintin. See the Variety article for more information.
Simon has also confirmed the roles at Peggster.Net:
QUOTE
Nick and I are very excited about it. Everyone is bound to make obvious comments about our physical differences but let's not forget we are working with the technology that turned Andy Serkis into a messed up Hobbit and a 40 foot Gorilla, coincidentally two things often used to describe me and Nick.