I've got an effect which is a fairly simple two-pass deal- but it involves rendering to a texture in the first pass. Is it possible to change the render target from within an effect? I would definitely appreciate the reduction in code duplication from C++ by being able to do both passes within HLSL.
I am pretty sure you can't do this -- you have to change the render target between passes from the CPU side of things. The list of effect states that can be manipulated by effect files does not include anything regarding the render target.