Hmm – the +1 button started automatigically showing up in my blog today, since I use Blogger (which is owned by Google). The +1 button now appears if your Blogger blog settings include the use of share buttons; see this page for more Blogger +1 details, and this post for an overall +1 launch update.
The +1 button is shorthand for "this is pretty cool" or "you should check this out."
Click +1 to publicly give something your stamp of approval. Your +1's can help friends, contacts, and others on the web find the best stuff when they search.
Now we’re going to see the following options on many popular sites (this example is from TechCrunch)