this one's gonna be an interesting one to see how Google does it since Facebook pretty much trained people on how to work the 'like' button and forced people to be logged in to their site.
when people are doing a search on google, the last thing they are thinking about is hitting that +1 (like) before they even see the site. Then even if they like the site, are they really going to go back to the search, re-enter the term just so they can hit the +1 button? that's pretty doubtful.
it's definitely going to get gamed or attempted, but since Google Buzz didn't hit the mark the way they wanted it, it seems like this is a temporary fix to phase that one out while Google tried to catch up to Facebook. They are even attempting to do the +1 for adwords which seems a little crazy since who will +1 (like) an adword ad???
basically, there will be a nice surge in people on here who great gmail accounts since most newbies will assume that by doing this and hitting +1 plus along with making sure all those gmails are interconnected for that friend network they'll be soaring in the SERPS. With so many missteps continually going on with Google, I'm wondering if this thing will stick.
Remember some months ago Google tried this with the search results when they had the vote up button on each one? That went away rather quickly so we'll see how this one pans out.
Someone will come up with a service on here I'm sure, but is it going to be worth it in the long run?
We'll see what Google attempts next in their chasing of the Facebook dollar.