After suffering a painful and recurring system-crash, I tried installing a fresh svn checkout on a new ubuntu 7.10 (x86_64) but was unable to compile pgadmin. Although I got around the issue, the frustrating thing was that the configure script kept insisting that software A was missing when actually it was a (dependent) software B that was missing instead.
I don't know if it helps but this is what I noted during this ordeal. (I don't know if this is normal but I thought that mention of this in the INSTALL file could have been of immense help to me)
./configure Error was about postgresql missing when actually libpq-dev was missing Error was about libxml2 when actually libxml2-dev was missing Error was about libxslt when actulaly libxslt-dev was missing
./configure --enable-debug Error was about libwxgtk2.8 missing when actually libwxgtk2.8-dbg / libwxbase2.8-dbg were missing.