We've added a couple more malware data sources to the PH list:

http://www.surbl.org/lists.html#ph

6/27/09: As of 27 June 2009, the PH list includes ZeuS Tracker malware host data.

https://zeustracker.abuse.ch/

10/18/09: As of 18 October 2009, data from Malware Domain List has been added to the ph list.

http://www.malwaredomainlist.com/

Most of the data sources on the PH list are filtered to exclude significant sites that are cracked or abused. This is to reduce potential false positives on sites that are abused, but may be mentioned in significant volumes of hams.