Additionally, the minimum weight has been raised from 620 kilograms (1,367 pounds) to 640 kg (1,411 pounds) to make way for the return of KERS, and the safety car rules have been clarified to disallow passing on the last lap of the race even if the safety car comes in. The 107% rule, not seen since 2002, has been reintroduced to remedy the backmarker situation. However, if it were in force during the Canadian GP only Karun Chandhok would have been disallowed. And, the rule allows for a special dispensation if a driver sets a fast practice time, but can't match it in qualifying.
A development certain to be as big as the rest: Pirelli has been named the official tire supplier for F1 for three years. Bridgestone is stepping out this year even after Bernie and the teams asked the company to stay. Other makers like Hankook and Cooper got in the race, but didn't get very far. Michelin also considered joining, but wasn't interested in being sole supplier and wanted a tire war. After a 19-year absence from F1, Pirelli and its new family have a lot of work to do.
[Source: F1 Live, BBC]