patch to prefer native implementation
I have a patch that allows the wikibits.js getElementsByClassName to make use of a native version of that function when available. (FF 3, Saf 3.2 and Opera 9.5 all provide this function now). There is no loss of functionality.
To get an idea of how advantageous this can be: http://webkit.org/blog/153/webkit-gets-native-getelementsbyclassname/