Works, uses secure mozilla server Rated 5 out of 5 stars
For those who are whining over data tracking and 'sending URLs', the new version uses a secure mozilla server (heartbleed.prod.mozaws.net) to check for status. (http://whois.domaintools.com/mozaws.net). And it doesn't send URLs, rather the domain names.
When Heartbleed news broke out, a lot of good-willed people wrote tools to warn people (notably Filippo's checker). Most of the add-ons relied on his server to check the status. Both the checker and this add-on are publicly licensed and you can view and modify the code . All these were from the people who didn't belong to any tracking corporation or had any private interest, and they have done a favor by writing up tools/add-ons in a short time. For those who are still not convinced, they can launch the checker on their host (https://github.com/FiloSottile/Heartbleed) and point the add-on to that.
So, thank you, Kris.