Here's how it works:
When you land on the Google Jobs search page, you see a blue banner at the top of the page asking you to integrate your Google+ account with Google Jobs.
After you authorize Google+ integration, you will then see a new results page featuring positions best suited for you based on information from your profile. This data can include any previous jobs you've added to your Google+ profile, your location, and, it seems, connections and interests. In my case, I saw a lot of jobs for technical writers. But I also got suggestions for engineering positions, which I am in no way qualified for. I can only guess these jobs were added because of the people I have in my Google+ circles and communities I've joined.
On the left-hand side of the job search page, you have filters to narrow your search by location and specific teams inside Google. On the right-hand side, you will see people at Google you may know and a button to add them to your circles. And, according to Google Plus Daily, which first reported on the new Google+ integration, you will also see people who work at Google and are already in your circles.
If you apply for a job, your basic information including name, education and current job are automatically filled out for you, making the application process a little bit faster.
Google+ integration seems like a handy feature, but the idea of integrating social networking data into the job process still makes me a bit squeamish. Especially given how easy it is for online photos and other posts to leak out unintentionally. Not all social networks are created equal, however, and some are entirely appropriate for the professional world.
LinkedIn, of course, is designed for this exact situation. The professional social network has a similar feature to Google's that lets you apply for a job with just one click populating an application with data from your LinkedIn profile. The difference, however, is that LinkedIn is designed to be a social network that shows off your professional side. It lets you put your best foot forward by emphasizing your employment record and education, and puts less emphasis on your monthly heli-skiing trips with the college crew or your penchant for knitting cat sweaters.