WordPress is urging anyone who has a self-hosted WordPress blog to update as soon as possible. (Your blog is self-hosted if you have it installed on your own domain. If your blog url is something like yourblog.wordpress.com.)
The tactics are new, but the strategy is not. Where this particular worm messes up is in the “clean up” phase: it doesn’t hide itself well and the blogger notices that all his links are broken, which causes him to dig deeper and notice the extent of the damage. Where worms of old would do childish things like defacing your site, the new ones are silent and invisible, so you only notice them when they screw up (as this one did) or your site gets removed from Google for having spam and malware on it.
For more information, see the WordPress blog.