I think it is pretty much time to give up on XML formats or microformats taking hold, for anything like standard consumer use. If we can't get our act together for resumes, we'll never apply it to recipes.
Too bad, though, I think it would be nice to have recipes more standardized. There could be various optional sections, such as Prep in Advance. I would like to be able to search by that--when I'm in a hurry, I don't want recipes that require marinading for 4 hours.