This isn't an exploit, it is a feature of almost every modern browser.
Applying different style to visited links is a feature. The trick to pull the info back to server is an exploit.
I wasn't aware that sharing your browser history with every website that cares to check it was a 'feature'.
I keep up with most tech-related news as well as I can and I had never heard of it until now...
I'd be interested to see how many people actually have heard about it before.