The same guys who hacked (and continue to hack) iPower-hosted Web sites appear to be behind the phpBB and phpNuke attacks. They're also targeting outdated, vulnerable WordPress installations, leaving message board spam and Weblog spam advertising poisoned Google Groups, and leaving links to Zlob droppers in places like Facebook and MySpace.
The compromised PHP forums are merely the tip of the iceberg, and many of them do not rely on JavaScript to download copies of the zlob Trojan. The compromised PHP forums, WordPress installs, iPower Web sites, Facebook profiles, and so on are the inputs to a large and rapidly-changing network of servers, mainly hosted in Eastern Europe, that actually do the dirty work. A user coming in from a PHP forum or a compromised Web site might be redirected straight to a virus downloader, but usually he isn't; instead, he's redirected to a traffic manager site, which then silently redirects him, often through two or three intermediary servers, to the final destination, which hosts the exploit software and the malware it downloads.
A handful of these servers will look at the browser's user agent, and attempt to download the Macintosh DNS changer malware onto Macs as well.
I've documented this underground network, complete with flowchart, extensively at
http://tacit.livejournal.com/240750.html