Do You Use Microformats, RDF, Dublin Core Or Another Type Of Semantic Markup?

Do you use any of these technologies? Which ones are current and hence sensible to include in a site?

Documentation on any seems to be relatively sparse, and usage of any of them limited, as search engines get better, are they even relevant any more?

I use microformats whenever I can. Usually it just makes sense anyway, as frequently when I have an address block, I may want to style some elements differently then other elements, and that makes it super easy. It's not like microformats are that hard to figure out.

There has been a couple of instances where, because I was using a microformat, I was able to re-use the markup of a certain portion of a site somewhere else (as an include), and not have to change the markup, only the styling.

Finally, ever since I really stated exploring microformats, I got better at writing semantic markup and better at naming CSS classes.