Microformats: Still Relevant?

Relevancy always depends on your use case.

If you are setting up a new system, it's almost always better to use a predefined format for common data structures instead of rolling your own - why do the hard conceptual thinking when someone else has done it for you? As an added bonus, using them, you can already claim interoperability with other services ("based on the h-recipe format").

If you want your stuff to be indexed by Google, it's good to use their format.

Are all of these widely used at this moment? No. Some even seem useless as compared to more widespread format (looking at you, iCal wannabe h-event...). And some ... look pretty much like a reskin of a preexisting format under a new name (XOXO?). Doesn't mean they aren't relevant.