just for the records:
truns out i had to manually remove those libqt4-maemo5-* packages which still were at 4.6.2.
no idea how that happend, but i put it down to NOKIA's way to break everything they took from Debian ... (just like my beloved error
The following packages have unmet dependencies:
upstart: PreDepends: sysvinit-utils (>= 2.86.ds1-23) or
busybox (>= 3:1.6.1.legal-1osso8) but it is not going to be installed
E: Error, pkgProblemResolver::Resolve generated breaks, this may be caused by held packages.
which remains apparently unfixable
)