I'd wager Zuckerberg is fascinated by Bitcoin, but I believe Facebook, for regulatory reasons, will not deeply integrate Bitcoin, e.g. native bitcoin tipping. If it does accept Bitcoin, it will only be as a payment method for buying its services (e.g. ads).
I'll most likely be just this.
I highly doubt a tipping service will be implemented, since someone would surely go nuts.
A good benefit, however, would mean that those who sell Facebook likes will start getting a lot of business, since people will want to promote their content in hopes of getting more tips.