This system is currently in prelaunch, so you would have to sign up to get notified when they decide to release it to the public.
I know what a [tag]tag[/tag] is and I know what a [tag]ping[/tag] is, but when you combine it, I am not really sure what this system will be. My guess is that you use different tags, and when you ping using these tags, various sites and search engines will index your site and update it using these tags.
If this is the case, will this be any different from what you do today? When you update a post in wordpress, and you use one plugin where you can make tags to [tag]technorati[/tag], your post will get updated at technorati based upon the tags you chose.
This new tag ang ping might be using this method to many sites/search engines? I am not really sure. If you want to get notified when they release it, submit your first name and primary e-mail.