“If it ain’t broke, don’t fix it” is a rule by which to live. Google Plus Your World launches today, and will roll out over the next few days to everyone. Basically it is a huge change in searches on Google, and it incorporates not only searches from the public web, as usual, but also searches that have been shared with you privately.
Personalized and social search results are not new to Google. They have been around since 2005 and 2009, respectively, but not included in the regular searches. Now personal, social and public algorithms are all rolled into one happy (for some) search algorithm.
For more detail, you can read all about it.