Maybe imlib could be linked against libpng.so.3 again, since gnome-core & gnome-libs, among other packages, do now require libpng.so.3 too ?
Ack! gnome-libs is not supposed to require libpng.so.3. I'll have to investigate what went wrong. :-( gnome-libs is supposed to link to libpng10.so->libpng.so.2
The png mess got sorted in the end, though I think it might reappear...