I've just updated a JUCE project from version 3.0.5 to the latest tip and I had a couple of build errors that seem to be related to the 10.5 SDK.
First, in juce_mac_FileChooser.mm on line 178 it couldn't recognise "NSModalResponseOK", so I changed this back to "NSOKButton" as it was before, and this seems to be ok.
Secondly, in juce_mac_NSViewComponentPeer.mm on line 1797 it couldn't recognise "NSApplicationPresentationDefault". I'm guessing that the windowDidExitFullScreen() function is only applicable to OS X's full screen feature, which I seem to remember was only introduced in 10.6, so I just put a "#if defined (MAC_OS_X_VERSION_10_6) && (MAC_OS_X_VERSION_MIN_REQUIRED >= MAC_OS_X_VERSION_10_6)" around this line to fix it.
Can you verify tht these fixes are OK? Hopefully I haven't broken other things in the process!