Even after applying your patch I had a little trouble getting everything to link properly on x86_64 Fedora (14). I ended up manually tweaking my make files after running qmake.
Changed the LIBS line (in MLDemos/Makefile, _AlgorithmPlugins/<n>/Makefile.<n>, _IOPlugins/<n>/Makefile.<n>) to:
I think the issue we're all having stems from the structural redesign of opencv 2.2. Everything has been split up into smaller headers, and the functionality is similarly separated into different shared libraries. It's a more logical code structure, but it means that we need to have different makefile rules for pre-2.2 and 2.2+ code.
As far as -lhighgui -lcv -lcxcore is concerned, those libraries don't exist on my machine anymore. "highgui" is "/usr/lib/libopencv_highgui.so", and so on. That would explain why my 'fix' didn't work for you.
Changed the LIBS line (in MLDemos/Makefile, _AlgorithmPlugins/<n>/Makefile.<n>, _IOPlugins/<n>/Makefile.<n>) to:
LIBS = $(SUBLIBS) -L/usr/lib64 -L/usr/local/lib -lhighgui -lcv -lcxcore -lQtGui -lQtCore -lpthread
I suspect there's an easier way, but this at least allowed me to build and everything seems to work properly.