(reminds me that I still need to add the USE_UPNP option)
Note that qmake is a pretty simple tool, optimized for conveniently building Qt applications in a cross-platform way; it in no way compares to cmake/autotools or another "full" build system. But it's enough for building bitcoin-qt on the supported target architectures so that's good enough for me... For "bitcoind" and "bitcoin-wx" you probably want to keep around the makefile.