Initial publisher partners whose sites are adding +1 buttons include Reuters, Bloomberg, TechCrunch The Huffington Post, The Washington Post, Mashable and Best Buy.
The company will also install +1 buttons at its YouTube, Blogger, Android Market and Product Search services.
The +1 button is Google’s answer to the ubiquitous Facebook “Like” and Twitter “Re-Tweet” buttons found on publishers’ websites.
Initially, the company added +1 to its search results, so that users see recommended sites when conducting searches.
http://tinyurl.com/3ewwum9 (Google blog)