Creative Comments: On the Uses and Abuses of Markup This pretty much says the same things I've been saying of late such as, "The Semantic Web isn't a replacement, it's a supplement.". I'm not going to bother bringing a whole lot of context here as the article is actually about the Creative Commons' (and apparently Trackback's) misuse of the comment tag and embedding RDF into HTML.
"Surely, I wondered, they know that putting RDF into HTML comments is an inelegant way of relating human and machine-consumable resources? Creative Commons, which has taken on the laudable task of creating RDF descriptions of common licensing terms for intellectual property, suggests its users associate machine-consumable licensing terms...with the web resources to which they apply by embedding RDF directly in HTML comments...In short, markup language comments are for communicating with humans, not with machines. The problem with incoherent strategies is that it's not always possible to predict all the ways in which they will fail or go bad."
It's a shame that a really good use of RDF has decided to do it in such a non-standard, if simple way. RSS is a really good example of how this separation is good. New proposed standards like SMBMeta (or Whoogle) propose the same thing. The author suggests the link tag to link to the licence. I guess you could also use the meta tag to embed the extra metadata.
Using this example:
<meta name="dc.title" content="Anti-war demonstrators">
<link rel="schema.dc" href="http://purl.org/metadata/dublin_core_elements#title">
<meta name="dc.date" content="2002-09-28T14:36:54">
<link rel="schema.dc" href="http://purl.org/metadata/dublin_core_elements#date">
This is using the Dublin Core Guide.