I'm going to be buying an iMac shortly. I also have a Macbook with Snow Leopard. Ideally, I'd want to upgrade this to Lion at some point in the future. I'm a little unclear about what Apple will supply with the iMac once Lion is released. Will Lion be available on a physical media (ie. CD) for reinstall purposes and, if so, can I use this to upgrade my Macbook? I realise it's only $29, but it's a bit of a nuisance if I have to spend money on a OS that I already own just to upgrade my Macbook.