ooooookay... looks like the problem was somehow on my end.
this debian box got upgraded from squeeze to wheezy like 2 months ago.
I'm not really sure what the solution was but i did this:
- installed the upnp libs (before, i always compiled with USE_UPNP=0)
- apt-get auto-remove'ed left-overs from Squeeze (lots of old boost libs got removed)
- restarted

now the git cloned source and the zip-DL source compile and work...

thx a lot!