Hi Matthew, I'd take the freedom to disagree with you; as far as I know, the CC BY-SA licence (version 3.0, but also all the previous ones) does not require linking to its text (at http://creativecommons.org/licenses/by-sa/3.0/), not to mention pasting the whole text.
The only requirement is to attribute the author in the way specified by him/her, and in our case most of the time this means to mention the name of the author and the name of the licence. But taking into consideration Facebook's Terms of Use, it would obviously be safer to link to the licence, agreed.
On the other side, I would really like to see a legal case against Facebook, because it really seems weird if they could get a "non-exclusive, transferable, sub-licensable, royalty-free, worldwide" licence for all content that is uploaded to their servers, especially if they could overrule a free licence like CC BY-SA simply by having such a phrase in their Terms of Use.