Google is taking on Facebook with a Like button of its own. The plusone button launched yesterday will be rolled out across all Google search results and will allow your friends
1) It’s a little button with a +1 on it that pops up next to search results. Click on it to recommend something you like.
2) Yes, it is like a Facebook Like button. It provides social context to stuff on the web -say your friend Tom +1s a search engine result for a hotel in Barcelona, you’ll see his recommendation when you search for hotels in Barcelona.
3) It uses your Google identity to work out a) your name, b) your friends. Your friends are the same as your contacts in Gmail’s G-chat. You will need to be signed into Gmail or Youtube for this to work. But lets face it – you probably already are.
4) The +1 button might do better than the Facebook Like button because it’s lower impact. My friends will only get my opinions on Spanish hotels when they are searching for Spanish hotels, therefore I’ll be more likely to recommend more things because it will only pop up when it’s useful to them.
5) Third party websites will be able to embed the button – which will encourage a rapid adoption. Just like the Facebook Like button, this is going to be key for blogs, news sites, online shops in getting their pages and products out there. There is a strong incentive for commercial sites to adopt this and work themselves into the user’s social context. More +1 recommendations will also improve the SEO rating of a site. It’s a no-brainer for site owners to introduce this..
Google explain on TheGoogleBlog