Infact you could go back a bit too, since Whatsapp was bought that way too. I very much doubt the original facebook has much value - it's all in this new stuff. But there was very real value acquired.
If there was no value before, then they got all of that for free - and with it very real cash flows and very real money. Mind you too, facebooks revenue hit above $117bn and profit actually went up.
Also i'd love to be on the other end of a deal where I got something like that in exchange for 'nothing'.