I have put a new gpc snapshot at:
http://www.math.uni.wroc.pl/~hebisch/gpc-20070904.tar.bz2
This snaphshot contains mostly bugfixes. Main feature is that gcc-4.1.x support is now integrated.
NOTE: there is a change of licence: this snapshot uses GPL version 3.
For new features see:
http://www.math.uni.wroc.pl/~hebisch/gpc/NEWS-20070904
and for fixed bugs:
http://www.math.uni.wroc.pl/~hebisch/gpc/Fixed-20070904