The reps went on to say that the technology that exists to convert 2D material to 3D on the fly wasn't good enough to supply material for the channels... yet. That's a relief to anyone who cares about what they're looking at (read: everyone), but it severely limits the content available. Looking above at the screenshot of DirecTV's channel guide this morning, you can see Cine3D (channel 104) showed Under the Sea 3D twice in a row, probably not because it's such a barn-burner.
One other slight caveat: the video quality isn't quite as good as 3D Blu-ray since there's less bandwidth available. (DirecTV uses "side by side" 3D tech while 3D Blu-ray is sequential — check out this article for an explanation of the difference.)
Still, having an actual selection of 3D channels is better than none (or one), and everybody who has a DirecTV HD box should start seeing the channels today. To actually experience 3D, of course, you need a new TV and some silly expensive glasses. It would also help if you have a taste for things that look really bewildering.