Now that we've established that the number of commits only gives us limited information about the contribution of various people/groups, can anyone familiar wit

Now that we've established that the number of commits only gives us limited information about the contribution of various people/groups, can anyone familiar with the webkit codebase give us a "state of the union" about who's actually improving Webkit most these days? What have been some of Google's biggest contributions in the past 6 months? Apple's? RIM's?