This news came a few days ago... Google is officially supporting the Good Relations (e-commerce) ontology as a source for Rich Snippets.
This means that once we have a good mapping for it in Drupal Commerce, sites that use Drupal for commerce will be at a distinct advantage. Yahoo research showed that click through rates for rich snippety search results were 15% higher, and other research has shown up to 30% higher.
I think that this will be increasing the conversation about RDFa in general, so it will be great if we can have the proper markup in place when people start talking about it.
I have posted an issue in the Drupal Commerce queue, if anyone wants to pop over and start looking at how to incorporate the mappings into Drupal Commerce :)