I would love to find a way to exclude content from certain portions of a public page, but I don't believe that exists (embedding it in an iFrame kinda works).
What I can gather from article you linked, the "googleon" and "googleoff" tags are exclusively used for enterprise content that is being crawled by "Google Search Appliance" which seems to be a google powered site search. The results aren't displayed in Google Search, just your enterprise's local site search results powered by the "Google Search Appliance".