It's only valid for pages built with FBML. So it's good for tabs (sections) but not for the main page itself. The main page is a newsfeed where you just can't p

It's only valid for pages built with FBML. So it's good for tabs (sections) but not for the main page itself. The main page is a newsfeed where you just can't put any FBML. So it makes an interesting tool to track subpages but in general it's pretty useless. Clever idea though.