encyclo - 1:22 pm on May 3, 2007 (gmt 0)

Firstly, it's an attribute value, not a tag, despite what Yahoo are calling it. Secondly, as Yahoo are supposed to be Web-2.0-Savvy, where's the properly-defined microformat [microformats.org] for this invention? Yahoo have not chosen to use the robots-exclusion profile [microformats.org] (which has never got past the draft stage and is totally unsupported), although they have taken the same approach of defining a class to ensure that the markup can validate.

I really don't like the fact that they are using a "<p>" tag...

You can use any element that accepts a class attribute, not just a paragraph. The example markup given by Yahoo is formal on that.