I cannot find confirmation on any of the docs pages - does the new Open Graph Beta include new meta tags, other than those defined on the OGP page?
You can find a list of the OG: tags Facebook is using mid-way through their documentation page at http://developers.facebook.com/docs/beta/opengraph/tutorial/
While it's close, there are a few tags not shown on the OGP page such app_id which is obviously required. Type is also used to hold the namespace for the action rather any descriptor.
In addition as you define actions & objects [dates, prices, additional string fields, etc] you can use corresponding tags to provide data for them.