I think it's more than that. Not too long ago, Facebook acquired Karma (
http://getkarma.com), which had quickly become one of my favorite services because they made gift-giving into a fun and dead-simple process. In fact, it was addictive - I remember sending at least three gifts within the first two weeks of downloading Karma on my iPhone. And since Karma was already built on top of Facebook's social graph, the acquisition made perfect sense and enhanced the overall experience even more for its small but loyal users. I think introducing a gift card was the next logical step to bring it to the mainstream.