With all the latest improvements to social networking it was only a matter of time before it started to impact search engines. The leader is search engines Google just announced their own social network type site called +1. This system allows you to add a +1 to search results and see what your friends like and rank pages as well. This works for search results and for paid adwords.
The important thing to note here is the continued push to making sites interactive and what I like to call web 3.0 the future of social networking and social search engines. These will impact your rankings as Google now puts more emphasis on how many people like your pages etc.