Hmm, sounds like another package is conflicting with this (maybe the latest CSSU Qt update?). Try from the command line:
apt-get -f install
And that should tell you which package it is conflicting with.
qt4-declarative-qmlviewer is only there for the "preview" qml interface (which I don't recommend using anyway), so you could force the upgrade if you're so inclined (I'll push an update to remove the dependency).

@jer006: as Neal mentions, the N9 version is coming. It's still got a few odds and ends I'd like to tweak before releasing a beta version.