There’s a Facebook worm circulating today. Nick Fitzgerald, Emerging Threats Reseacher at AVG Technologies has blogged it at http://fitzgerald.blog.avg.com/, and Roger Thompson, Chief Research Officer at AVG, has blocked the worm site.  Facebook is working on fixing the worm.  AVG’s LinkScanner (which is included in all AVG 9.0 products, or as a free product) protects by blocking the launch site.