I ran across this yesterday and tried it out.  Stuff came out decent but still not in the same quality range that you get from a 3d package.  Heres the link if anyone is interested.  It seems to take a normal map and convert to to a ao.

http://www.filterforge.com/filters/4517.html

The next update of Topogun will have occlusion baking. It will also have a non destructive workflow with Mudbox.

That is absolutely right. :) The next TopoGun release (which is almost ready) will have a maps baking module (normal maps, hardware ambient occlusion maps, software ambient occlusion maps, displacement maps, cavity maps and color maps transfers). Some of the advantages are:
-true multithreading support for maps baking (so the ones with quadcores will REALLY see huge differences);
- 32 bit floating point dispmaps (means no messing with displacement values in your renderer, just plug the map in your displacement slot and you’ll get exactly what you should, with a much higher dynamic range, compared to the normal 8 bit dispmaps)
- 32 bit floating point ambient occlusion maps (that means you can adjust your map and get less dithering results. You basically have a wider dynamic range, so the levels, contrast, exposure adjustments and so on will be less destructive).
-The hardware ambient occlusion maps look like the fastest ambient occlusion maps baking method available at the moment. On a Nvidia 7600 GT video card, you bake an ambient occlusion map at 1024X1024 in about a minute, for about 1 million triangles.
-Having all the maps baked (almost) simultaneous within the same raycasting engine ensures that all the baked features match between different maps (a pore or a wrinkle will always appear in the same place over the normal, dispmap, ambient occlusion map etc).
You can watch a video at http://www.topogun.com and see what’s about the TopoGun’s to Mudbox exporting features (you basically export a highres retopologized mesh to Mudbox and reconstruct all it’s subdivision levels).

just awesome PixelMachine!

Any details on the color Maps transfer?

I am looking for ways to get Zbrush like shaders baked to textures.

Well you can transfer a color map created for the highres reference mesh’s uvs and then transfer it to another lowres model, with totally different uv’s. So you’ll probably can bake the materials in ZBrush within an arbitrary uv’s layout (like an auvtiles generated one), and then transfer the results to a more coherent uv layout.

http://www.rusteddreams.net/faogen.html

You can try this for baking AO maps using your GPU, it’s pretty fast.  A friend used it on a contract where they had large scenes that were taking too long to bake with MR in Maya.