Apple are not open source friendly, no matter what people claim.
The Windows port of WebKit that Apple did apparently depends on some non-redistributable closed source libraries (Windows ports of CoreFoundation and CoreGraphics, by the looks of it). Richard Stallman would not be happy. (I'm pretty sure that it's also a LGPL violation, and anyone who contributed significant code to KHTML before Apple forked it could make life really, really interesting for Apple.)