Catch a Bug, Get Money
Tesla is also offering cash rewards (on specific things) if said hacker is able to breech the system in any way.
“Tesla values the work done by security researchers in improving the security of our products and service offerings. We are committed to working with this community to verify, reproduce, and respond to legitimate reported vulnerabilities. We encourage the community to participate in our responsible reporting process.”
Tesla Motors is looking for hackers (the white hats) to help find weak points in the Tesla Model S and other Tesla properties (like its website, Twitter account and so on).
This is similar to Tesla bringing one of their Model S EVs to Defcon later this year for hackers to try to gain access into parts of the car. It's obvious that Tesla takes security extremely seriously, based on how pro-active they are in taking all the necessary precautions to shore up security.
Unfortunately, Tesla Motors' website & twitter account were hacked just recently, so this is likely one of many reasons why Tesla wants to go all in on the security front.
Aside from the few photos here, you can find further info in the link here.