Short version:
Is anyone aware of a software solution that will scan an image and give it an overall focus score? Bonus if it can run as an Aperture plug-in. Basically, I'm looking for a solution that will help speed up my culling workflow.

Long version:
I know that there are imagemagic and MATLAB libraries that can do complex image analysis and with a fair bit of programming can create a score using the mathematical equivalent of the old Photoshop “Find Edges” filter. That said, with all the software out there that deals with boosting definition, lowering noise, etc, you'd think there would be something pre-rolled that could help detect out of focus images within some threshold, and tag them with a keyword or custom EXIF/IPTC field.

I've searched around a bit and haven't found much, so I thought I'd open it up to this crowd and see if anyone has come up with interesting solutions (Aside from paying an intern peanuts to go through all the images manually :) )

Cheers,
Rob