Compiling gnome-core-1.4.1 says it doesnt find libpng.. This is because libpng now requires libm to be compiled in the program (at least on my system).. This can be fixed easily (or are you doing to update it to 1.4.2 soon anyways?) replacing + -lz) with + -lz -lm) does the job
I find that this is broken in gnome-core-1.4.2 also. Recompiling the lowest version of libpng on portage...libpng-1.0.12-r1 is a quick workaround, but I don't want my gnome-core being built on such an outdated libpng. It sounds like you have an idea of how to make this work, but would you please post a little more information on how you got it working?
http://bugs.gentoo.org/show_bug.cgi?id=9792#c2
*** This bug has been marked as a duplicate of 9792 ***