[basseq]

To be honest, I thought of FiftyThree first, too, when I heard the Facebook announcement. Reading between the lines on this blog post, it doesn't sound like FiftyThree has any legal claim or trademark to hold against Facebook (even if they wanted to litigate).

Facebook has already "gone live" with the Paper name—I think it's too late to change it. Whether it's malicious (are they "building their story" off FiftyThree's work?) or not ("Oops") is almost irrelevant here.