netmeg - 2:43 pm on Apr 3, 2013 (gmt 0)
None of my users are on Google+ (and probably never will be) but I still maintain a page for each site, for authorship/publisher reasons, and in case something changes in the future. It doesn't cost anything other than the time to set it up, and tools are starting to come out now that post directly to these pages. I don't know if it will help rankings; my rankings are pretty good now, but I do notice that if I have a recent post to the Google+ page, certain queries will show my page and logo over in the Knowledge Graph spot, and that's a huge eye catching result, so if they're doing that, I'm gonna take advantage. It doesn't show up for every query or every site, and maybe they'll take it away, but for now, I'm there.
(Facebook is a different matter; my users are all over Facebook and they share and bring more users to the site. Plus I can treat the FB page fans like an email mailing list)