To me, it's much closer to communicating agreement in Apache open source projects. Someone proposes an idea or expresses an opinion, others simply respond with

To me, it's much closer to communicating agreement in Apache open source projects. Someone proposes an idea or expresses an opinion, others simply respond with "+1" instead of a variety of ways of saying "Yes/agreed/I concur/indeed/I second/I support/Let's do it" etc. So I got the same thought that pathik did - the +1 feeds my personal image of Google as primarily run by engineers.