I installed the build-essential with :
sudo apt-get install build-essential
then retrieved the Qt4.8 source from the Qt's website and compiled it with: (I tried to remove all the options I wouldn't need)
./configure -v -embedded arm -prefix /usr/local/Trolltech/Qt4.8arm -opensource -nomake demos -nomake example -nomake tools -nomake docs -nomake translations -no-multimedia -no-audio-backend -no-phonon -no-phonon-backend -glib -no-mmx -no-3dnow -no-sse -no-sse2 -no-largefile -no-gtkstyle -no-qt3support -no-cups -no-nis -no-freetype -no-gui
but I'm getting an error. It seems that the "arm-linux-g++" has not been installed.
I'm looking for people that managed to compile the Qt source on their Sheevaplug and all the steps you went through to compile it successfully.
Hope to have some replies :-D