Are NEX (APS-C) lenses necessarily bigger than micro 4/3?

I'm in the market for a compact enthusiast camera, like the GF1 or NEX. I'm thinking long term, like I'm buying into a family of lenses, so the body isn't as important to me as picking the right line.

I know that micro 4/3 cameras are going to have some problems (worse low-light performance, deeper DOF) associated with the smaller sensor size, which the Sony/Samsung APS-C compacts won't. But since size is a major factor, my question is: will the lenses necessarily, as a matter of physics, be larger for the APS-C cameras than micro 4/3? My ideal setup is a body with a pancake for the smallest possible form factor.

I'm leaning toward micro 4/3, as the cameras available seem more serious (though the GF2 is giving me doubts) as opposed to the oversimplified layout of the Sonys.