Title says it all. Do I need an ao pass to get ao or does cycles render that by default and the ao pass is just for extra control in post?
Well gee I didn’t know everyone thought my question was stupid 
Just have to give it a bit of time. Some people are doing their own thing… (If you’re in a real hurry sometimes Reddit or the Blender chats on IRC at Freenode are better suited. Many of the same people lurk there too.)
Anyhow there’s a few options with Cycles. You can enable up an AO pass under the render layers for compositing or being able to save it. Or if you want something relatively quick and idiot-proof there’s a toggle on the world settings that applies AO style lighting to the scene. (Not as a separate pass though.) And alternately if a mesh is dense enough you can setup vertex color to match AO. Cycles also has the pointiness output on the input-geometry node, which works similarly but without setting vertex color. And there’s even a way to bake it to textures, which can be handy for some things.
As far as I know, none are on by default. You have to go through menus or a particular process to enable them.
To add on to this, AO is not “required” for anything in Cycles - indirect light is already occluded correctly, as it is in all path tracers. While there are all sorts of artistic uses for the various methods pauljs75_ mentioned, if you don’t need them you don’t need to bother generating AO. See this for more info: http://mentalraytips.blogspot.com/2008/11/joy-of-little-ambience.html