From 2010: I’ve just fixed 2 blogs which I host that had been hacked. These are the first I have had hacked in more than 10 years of web-design and hosting.
Don’t panic, from what I can see this hack seems to be non-malicious and simple to recover from. This hack is not Wordpress specific. It just replaces the index files of whatever happens to be driving a site.
From what I can tell, only the index.php files on the sites where compromised. I’m still checking to see if I can discover how the hack came about.