OK, tried again with gcc 4.0.0 and got a little less errors:
/usr/bin/ld: Undefined symbols:
CFormat::operator wxString() const
collect2: ld returned 1 exit status
make[3]: *** [amule] Error 1
make[2]: *** [all-recursive] Error 1
make[1]: *** [all-recursive] Error 1
make: *** [all] Error 2
Any more ideas? I am still stuck...