WordPress has a new update. According to the site there was a security issue discovered in xmlrpc.php. They suggest updating ASAP or removing the file until you can. I’m not sure what the file does or if it will cause issues within WP so do so at your own risk.
Full details here: http://wordpress.org/development/2005/06/wordpress-1513/
EDIT – So, I just glanced at the xmlrpc file and it is pretty much the entire engine running WP so deleting it will cause a complete breakdown of the app. I’d go for the update ASAP option. Me on the other hand, I’m gonna ignore it till tomorrow because I’m lazy and Ben’s looking all cute and cuddly on the couch. 😉