I am using Qt4.3.3 for MacOSX 10.5, which is installed as system frameworks, not in /usr/local/... in the Linux sense. I use it with Xcode 3.0 IDE.
I also use Qt4.3.3 compiled from source, installed at /usr/local/.. and use this with qdevelop.
The reason I use qdevelop is that it is building an application skeleton for me based on the ui from the Designer. The reason I need the source version of Qt is that qdevelop needs a Makefile from qmake, while the framework version of Qt insists on creating a .xcodeproj project from the qmake command. The docs for qmake indicates that you can control this by the switches -mac or -unix, but this does not work, at least not for me.

The two 'versions' have coexisted without problems up till now.

Now I tried the Qt4.4 snapshot, built it from source and installed it as default.
qdevelop and make works fine, but the Xcode project is broken, the first error at this point,
right at the beginning of the ui_mainwindow.h created by the designer:
Building target “J51Viewer” of project “J51Viewer” with configuration “Debug” — (3 errors)
cd /Users/bnilsson/Documents/Programming/Active/Qt/tmp
/Developer/usr/bin/gcc-4.0 -x c++ -arch ppc -pipe -Wno-trigraphs -fpascal-strings -fasm-blocks -O0 -mdynamic-no-pic -fmessage-length=0 -mtune=G4 -fvisibility=hidden -fvisibility-inlines-hidden -gdwarf-2 -I/Users/bnilsson/Documents/Programming/Active/Qt/tmp/build/J51Viewer.build/Debug/J51Viewer.build/J51Viewer.hmap -F/Users/bnilsson/Documents/Programming/Active/Qt/tmp/build/Debug -I/Users/bnilsson/Documents/Programming/Active/Qt/tmp/build/Debug/include -I/Library/Frameworks/QtCore.framework/Versions/4/Headers -I/usr/include/QtCore -I/Library/Frameworks/QtGui.framework/Versions/4/Headers -I/usr/include/QtGui -I/usr/include -Ibuild -Ibuild -I/usr/local/include -I/System/Library/Frameworks/CarbonCore.framework/Headers -I/usr/local/Qt4.3/mkspecs/macx-xcode -I/Users/bnilsson/Documents/Programming/Active/Qt/tmp/build/J51Viewer.build/Debug/J51Viewer.build/DerivedSources -pipe -Os -w -DQT_NO_DEBUG -DQT_GUI_LIB -DQT_CORE_LIB -DQT_SHARED -c /Users/bnilsson/Documents/Programming/Active/Qt/tmp/src/main.cpp -o /Users/bnilsson/Documents/Programming/Active/Qt/tmp/build/J51Viewer.build/Debug/J51Viewer.build/Objects-normal/ppc/main.o
/Users/bnilsson/Documents/Programming/Active/Qt/tmp/build/ui_mainwindow.h:33: error: expected constructor, destructor, or type conversion before 'class'
/Users/bnilsson/Documents/Programming/Active/Qt/tmp/build/ui_mainwindow.h:474: error: expected class-name before '{' token
/usr/include/architecture/ppc/math.h:52: error: expected constructor, destructor, or type conversion before 'extern'
/Users/bnilsson/Documents/Programming/Active/Qt/tmp/build/ui_mainwindow.h:33: error: expected constructor, destructor, or type conversion before 'class'
/Users/bnilsson/Documents/Programming/Active/Qt/tmp/build/ui_mainwindow.h:474: error: expected class-name before '{' token
/usr/include/architecture/ppc/math.h:52: error: expected constructor, destructor, or type conversion before 'extern'
Build failed (3 errors)
I tried to remove what I could find from the Qt4.4, but the problem persists.
What can I do?
Rignt now I am rebuilding Qt4.3.3 from source, but I have little hope that it will work.