Does not compile on Mac with Qt 4.7 Beta 2

gcc -c -pipe -g -gdwarf-2 -arch x86_64 -Xarch_x86_64 -mmacosx-version-min=10.5 -fvisibility=hidden -Wall -W -fPIC -DQT_SHARED -DQTM_PLUGIN_PATH=\"/Users/axeljaeger/Downloads/qt-mobility-opensource-src-1.0.1/install/plugins\" -DQT_BUILD_BEARER_LIB -DQT_MAKEDLL -DBEARER_ENGINE -DMAC_SDK_10_6 -DQT_GUI_LIB -DQT_NETWORK_LIB -DQT_CORE_LIB -I/usr/local/Trolltech/Qt-4.7.0/mkspecs/macx-g++ -I. -I/usr/local/Trolltech/Qt-4.7.0/lib/QtCore.framework/Versions/4/Headers -I/usr/local/Trolltech/Qt-4.7.0/include/QtCore -I/usr/local/Trolltech/Qt-4.7.0/lib/QtNetwork.framework/Versions/4/Headers -I/usr/local/Trolltech/Qt-4.7.0/include/QtNetwork -I/usr/local/Trolltech/Qt-4.7.0/lib/QtGui.framework/Versions/4/Headers -I/usr/local/Trolltech/Qt-4.7.0/include/QtGui -I/usr/local/Trolltech/Qt-4.7.0/include -I../global -I../../build/Debug/QtBearer/moc -F/usr/local/Trolltech/Qt-4.7.0/lib -o ../../build/Debug/QtBearer/qcorewlanengine_mac.o qcorewlanengine_mac.mm
qcorewlanengine_mac.mm: In constructor 'QtMobility::QScanThread::QScanThread(QObject*)':
qcorewlanengine_mac.mm:169: error: call of overloaded 'QString(NULL)' is ambiguous
/usr/local/Trolltech/Qt-4.7.0/include/QtCore/qstring.h:428: note: candidates are: QString::QString(const QByteArray&)
/usr/local/Trolltech/Qt-4.7.0/include/QtCore/qstring.h:426: note: QString::QString(const char*)
/usr/local/Trolltech/Qt-4.7.0/include/QtCore/qstring.h:727: note: QString::QString(const QString&)
/usr/local/Trolltech/Qt-4.7.0/include/QtCore/qstring.h:106: note: QString::QString(QChar)
/usr/local/Trolltech/Qt-4.7.0/include/QtCore/qstring.h:105: note: QString::QString(const QChar*)
qcorewlanengine_mac.mm: In member function 'void QtMobility::QScanThread::getUserProfiles()':
qcorewlanengine_mac.mm:381: warning: unused variable 'itemDict'
make[3]: *** [../../build/Debug/QtBearer/qcorewlanengine_mac.o] Error 1
make[2]: *** [debug-all] Error 2
make[1]: *** [sub-bearer-make_default] Error 2
make: *** [sub-src-make_default-ordered] Error 2