While Apple has been a good open source citizen in the past, it seems they are having some issues right now with the Webkit source code release :
http://www.itworld.com/open-source/163197/apple-delays-release-lpgl-webkit-code
Unfortunately for them, since they aren't 100% copyright owners of the code, they do not have the right to withhold a source code release since the code is under the LGPL.
http://www.itworld.com/open-source/163197/apple-delays-release-lpgl-webkit-code
The Apple code in question is dual-licensed under the BSD and the LGPL... the latter license pretty much requiring a simultaneous release of binary and source code. So, this is not a decision Apple can really make.
Unfortunately for them, since they aren't 100% copyright owners of the code, they do not have the right to withhold a source code release since the code is under the LGPL.