PhotoBrain is a new image search engine from Matlab-K for Mac OS X (10.6.6 and higher). It costs $8.99 USD and is available worldwide exclusively through the App Store in the Photography category.
PhotoBrain on a local drive uses image/picture/photo identification technology, rather than keywords or metadata. The folks at Matlab-K say that Mac users will find it handy when the same images and photographs are multiplied in the hard drive, because they are duplicated, copied or simply renamed.