This was just today? Or when? I hope it wasn't before he did v1.5.3 update. I hope it was today... I want more updates. Moar moar moar!!!! I don't care what it is, just give me them! ^.^
It's a Facebook feature which allows people to earn 3 free tank coins per one friend installing SSL2 on their FB account. Read the v1.3.5 thread for moar infoarmation.
Actually it's also for people who play on the main site too, it just takes them to surveys instead of inviting people like the people on FB can.