It would useful to be able to run a development preset during export. This would be helpful whenever the export destination has unique development requirements. For example, I would like to take certain actions (reset exposure, vibrance, tone curve, etc.) when exporting to Phototmatix.
It would be super-easy to write an export filter (post-process action) to do this - maybe somebody already has (I'm not aware of it).
jdphog's example would not depend on relative presets, but it would be quite easy to add a relative adjustment sheet to the export properties, along with an absolute develop preset drop-down selection, savable as an export preset instead of a develop preset.
Why don't you do that for us Jeff? ;-}
Maybe I'll add this feature to DevAdjust some day...