Techie people post tech news on a site used by early tech adopters. Not sure how you build that out to the general public.
Anyways, I'm a tech guy, but also into photography (http://plus.google.com/104936988539783595605), and I must say G+ keeps me plenty busy, more then I've ever been on Facebook, where I sometimes cross post to, roughly, the same audience (non of my family members though are on G+ just yet). Actually, I like G+ for being useful, easy to use, and I give Google credit for listening and quickly adapting and evolving.
It seems like very interesting content from (and for) a small audience, draws a slightly larger audience, and they bring slightly more popular but also slightly less interesting content, and repeat until you have the reddit front page as it is today.