Ann_Smarty - 11:42 pm on Nov 5, 2012 (gmt 0)

Even without making a comment, any url that is +1'd is added to the user profile's "plusones" tab (which is public and indexable by default, but can be made private by the user).

It is not actually public. Try accessing your own https://plus.google.com/XXXXXXXXXXXXXXXXXXX/plusones when logged out

In my case, it redirects to https://plus.google.com/XXXXXXXXXXXXXXXXXXX/posts (the page where my public updates are visible)

And on other people's profiles I can't even see that tab.

There might be an option somewhere to make it public but I don't see one...