Last.fm Player is statically linked against qt-4, therefore doesn't depend on it AFAIK. I am running the latest version (1.1.4, found here: http://www.last.fm/help/player/download.php?url=http%3A%2F%2Fstatic.last.fm%2Fplayer%2FLastfmLinux-1.1.4.tar.bz2) and I only have qt-3.3.4-r8.
No, sorry, we are not using any static version, we compile it.