I say FOCUS because that is what it helps you to do: focus the indexed content of your pages.
Just when I thought Yahoo! was the most boring search engine, they introduce this interesting tool for content publishers. I have a few tests to reset, but I don’t mind. Yes it’s strange to use class attributes. Yes it’s weird to require a unique attribute inside content. But really, this isn’t a tool for the average website, right? This is a tool to be used strategically.
Now it’s up to Google to adopt it and steal the thunder back (I’d quickly skip Yahoo! again if Google supported this attribute) or will there be two search engines again?
Source: Search Engine Land.