To be fair, the patent has long expired. And you can't patent something like the look of a border. What they're attempting to sue over is trademark and trade dress infringement, which has a considerably longer life than a patent.
In any case, it might be hard for them to claim damages which are necessary in trademark cases, since Polaroid probably owes a lot of their recent success to Fuji. That, and didn't the Impossible Project just buy Polaroid? Apparently they didn't think it was trademark infringement a year ago when they were making film for Polaroids under their own brand. Or were they paying royalties for that? In any case, I'm sure Fuji isn't too worried about it.