There is a LOT of potential metadata.
If an SEO gets a job to apply these to a large, existing site the job of doing this work - in a top quality manner - could be onerous and mindnumbing. Screwing it up or sending it out where a halfass job will be done could cost you a lot of lost traffic and lost revenue. For a top quality site you want an erudite person doing this work - and the job will be ongoing.
How do you plan to do this work? If you look at how bing has marked up their SERPs with logos, ratings and other data drawn from the code. See this example from the video for avatar movie.
I think that this will be too important to ignore.... and if google starts to mark up their SERPs like the Bing example above it will be urgent to get at least your best content and most important products marked up and out there.
Probably a good idea to prepare a template for this information that matches your content and start using it right away.
Edited by EGOL, 09 June 2011 - 10:36 AM.