I love to play my ranger in Guild Wars 2! During the first beta weekend I only had my basic juvunile stalker pet. During the second beta I leveled up a bit and got out of Queensdale area and into the Kessex Hills map. This is where I ran across the animals that were tagged with a green name. Until this point I had only seen animals that were tagged red (aggressive) or yellow (non aggressive). Standing next to the green tagged animal will five you the option to press F to tame the animal, and *poof* you have a new ranger pet.
Once the game is live I will get specific locations down for each one I get and maybe record some video for it.