Protecting against Microformat spam

If you look at This comment on my site, it might look like nothing - but check with Tails, and you find a hidden spam hCard.

It's very easy to produce one and embed it in to a post or comment, which will then be indexed by sites such as Technorati.

So what can we do to stop this type of spam before it starts?

Disucss.

Infact, its' been posted here too:

Test

Some sex company

selling sexy things

20% off all items

This hCard created with the hCard creator.

Unlike my site, it does appear here as style="display:none" is not supported, however the hCard still exists.