...On the PC, that is. BioWare's Derek French has stated that both Spore and Mass Effect with require a form of online validation every ten days. If the validation is not done, the game will stop working. It is said that Spore will be using the same sort of idea.
While this is a great idea that will help prevent illegal actions, it may make it difficult for those without an internet to play a game. Hopefully, this won't be a problem.
Article