The 2012 canned tuna guide compiled by Greenpeace supersedes the 2011 guide. There are fewer choices contained therein, but a lot more pole and line caught options. It seems Greenpeace is not presenting the brands purely using FADs (Fish aggregating devices) for fishing.
The Greenpeace website offers an explanation of the ranking system and includes some of the following criteria.
The link to this page is on the Nourishing Nosh Sustainability page