It is indeed a Jetpack function, a little info here:
http://www.symbioguides.com/knowledgebase/jetpack-info-installation/Basically you make a free Wordpress account (this is so you can use their database functions for things like the Stats plugin which is fantastic) then go into your dashboard, click Jetpack and Connect to Wordpress.
There are lots of things in there you may find useful. On my symbio site I use the sharing buttons, stats and contact form. ....on all 16 images I have uploaded, can you tell I've been busy?

I'll be updating that tutorial with the Jetpack info and moving it to Symbiosguides soon, it's on the list now thanks!