Often, a photographer takes a numbe of photos in a row. It would be nice to have a side-by-side comparison with (at least) two different photos, with F-Spot making suggestions on which one is better in technical ways.
Groups of photos can be determined by:
Ways to determine image sharpness...
Compare the size of compressed files to see which is larger. Sharper images of the same subject under the same conditions are larger in file size.
Analyze edges (like the result of “find edges” in GIMP). Those pictures with the same subject (under similar enough conditions) with stronger edges overall should be sharper.