A while ago (actually, quite a while ago,) Raj Krishnan of the Google “snippets” team posted a very interesting article on meta descriptions at the Google Webmaster Central blog. One of the key points was about “tagging” your meta description.
The meta description doesn’t just have to be in sentence format; it’s also a great place to include structured data about the page. For example, news or blog postings can list the author, date of publication, or byline information. This can give potential visitors very relevant information that might not be displayed in the snippet otherwise. Similarly, product pages might have the key bits of information — price, age, manufacturer — scattered throughout a page, making it unlikely that a snippet will capture all of this information. Raj Krishnan
While this technique may not work at all well for purely information based content (this article, for example,) it seems like a fantastic way of demarcating your data for product-oriented pages. Not only does it create a very clear search snippet, you need to consider the possibility that Google may be able to better clarify or identify search results on the basis of tagged data. I don’t mean that your rankings will improve; Google has long been very clear on the point that meta descriptions are not used in establishing rankings. They are, however, used to establish relevance.
The article does not say that Google parses out this structured data and uses it. However, it is entirely likely and possible that they either use or intend to use structured data in such a manner.
Regardless, for products which are well represented using short blocks of structured data, such as books, movies or sound recordings, this can be an excellent way of quickly conveying all of the most critical data about the product. From a programming perspective, as well, this can provide an extremely easy and logical way of building unique meta descriptions for a large database of products without needing to write each one individually. If it’s effective, it could mean a significant savings of time and expense at this level of e-commerce development.
Of course, for meta descriptions, the only truly meaningful metric is whether they encourage qualified visitors to clickthrough to your site. Since descriptions aren’t used for ranking, only actual testing can confirm one way or the other how well a given snippet helps your site perform. I couldn’t find any examples of tagged meta descriptions in use on the various product searches I tried; I’d be interested to know if anybody is actually using this idea.
Does it help? No idea. Still, I think I’ll probably need to give it a trial to see what it can accomplish.