when they announce a expansion or game that is available for pre-order that means you can actually play it shortly after pre-ordering it because you are automatically in the beta test then and thus available to play and help within the test process so that you can enter your opinions (which is far better than what all the others do for pre-order) and once it is released you just get it updated with the final version and no cost! (because you already pre-ordered it)
you will need to get Impulse to download it and update it but it isnt required to be loaded to play:)
