http://dl.dropbox.com/u/14061228/gsoc_blender_retopology.pdf that is a document outlining some of the retopo features to be added this summer throughout GSOC
Affinity is closest to Photoshop when shopping image editing alternatives but it lacks automation beyond the most basic macro recording feature. No e.g. automated file I/O if that's something you need. To me it's the one major bummer with this software. Promises to add scripting in some upcoming version were made ages ago…