Just a reminder to those who have uploaded their photos to G+ about the printing options and G+ and it's partners making money off of your stuff. G+ enables downloading and printing "on" by default for your friends only. G+ doesn't specify exactly what "friends" are, are they just in your "friends circle" or are they people in all your circles!
So anyhow, to whom concerned, take a good look through all your settings when creating your profiles and make the appropriate selections. The photo printing and download settings can be found by clicking on the "photo" menu located in the black header across the top of your G+ page. Go to the right where the little gear icon is, click it and proceed to "photo settings" option. In the "Privacy and Permissions" tab is where you'll find the "Allow any visitor to:" section with tick boxes for "order prints" and "download".
The next section down you find the "Creative Commons" license section which should also be checked with your own discretion. At least it is set to "Do not allow reuse" by default IIRR.