Will the Mac OS X Lion come predownloaded on macbook pros?

I don't know a lot about apple and their software or about computers so i'm sorry if i sound stupid .. but i'm planning on buying a macbook pro for school and i'm hearing stuff about the new mac os x lion software coming out in july and i was wondering if it will come already on the laptop when i buy it like the snow leopard does once it comes out or will i have to buy it separately?