No, it’s not a mechanism to invite a friend or partner to a party…it’s the Google equivalent of the ‘Like’ button or ‘digg’.
Your +1s will show in your public profile, although you can keep them private if you choose to. Therefore, internet marketing companies should set up a public profile on a Google account so that they can add +1s for clients and valuable links. In addition, it seems that +1s will also be featured on PPC ads, as well as, shortly, on websites.
Find out more from the official Google video on +1: