Baking only light maps in Cycles I was super excited to see that baking functionality has finally made it into Cycles. But I'm a bit confused about its usage. There are a lot of options in there. I'm able to get baking working just fine I think, but I'd like to back just a light map. There doesn't seem to be an option to combine bakes (except for one big combination of every thing). So I'm guessing I need to bake multiple maps and merge them in Photoshop. I'm just not sure exactly which ones I need. I'm guessing it would be Shadows, AO, Diffuse Indirect, and Diffuse Direct? Am I missing one? Is there some way to have Cycles bake those four together at once?

As a side question, just because I haven't tried it yet, if I make a second UV channel for my light maps (say one using Lightmap Pack in the UV tools) and set the image that I light map on to use that one while keeping the actual materials on the first one, will that give me the results I want? I don't want my materials to go wonky when I create the second UV set but I've never worked with multiple UV channels before. Certainly not in combination with baking in Cycles.
We are doing the exact same thing, although my approach to the problem is slightly different.
Like you I created a second UV channel for the lightmap while handling the other materials on the first one. Once I unwrapped the object to the second UV channel I duplicate the entire object, remove all the materials from the clone and add a simple white material to it.
Then things start to get a bit complicated. Let's say there are several objects, for example a wall, a floor and a ceiling. When I bake the wall, I activate the clone of the wall, while hiding the original wall object. The original floor and ceiling objects stay active while their clones are hidden. This way you can retain the bounce light data that comes from the unchanged original objects.
It is basically the same procedure as having a second node tree in the materials except that you're switching on and off objects instead of node trees in every material on the scene.
I'm not sure if this is the smartest way to do it, but I don't have to bake several passes this way...