tmake/lib/linux-g++/tmake.conf is for X11 , and tmake/lib/qws/linux-arch-g++/tmake.conf is the right one for QTE("arch" is your cpu's architecture, you may use linux-generic-g++/tmake.conf for x86 or linux-arm-g++/tamke.conf for strongarm ).
Before you complier Qtopia example, you need set the environment variable TMAKEPATH to the right tmake.conf file.
eg: export TMAKEPATH=$QTDIR/tmake/lib/qws/linux-generic-g++/tmake.conf