BitWorking mentions the launch of the MicroFormats website, and asks a question about aggregators:

One question this raises is how does this markup survive a trip through an aggregator? I have done a little testing and found that Bloglines keeps class attributes intact. Are there exceptions? Do 'rel's pass through unmolested? What do other aggregators do?

Well, I certainly don't preserve the XML as it passes in BottomFeeder. As content is read and parsed, I create Feed and Item objects, and those are what get saved to disk. Keeping the original XML around would bulk up the save file size quite a bit, so I simply haven't seen a good reason for doing it. Unless the micro-content is in the description/content element, in which case it will still be present. What I ought to consider is some kind of user accessible extensibility system for defining things to look for...