Google made some improvements to the appearence of its +1 button. Now, when you mouse over the +1 button, Google shows a list of people who have +1’d the page. The feature is same like Facebook’s Like button with “show faces”.
The same list is now displayed next to the button if you change the code and select inline annotations. This is the new default option when you generate the code.
Google probably chose this option because you’re more likely to +1 a page if some of your friends already did that. But, before you select the deafult option, please note, it will take a lot of space depending upon the the number likes.