I’m just trying out GNOME on Fedora 18. There are two points to note about installing the Synfig binaries on here:
i) You need to install the old version of libpng (1.2) for Synfig Studio to work - this is not installed by default in Fedora and hasn’t been listed as a dependency in the Synfig Studio rpm package
ii) In Fedora 18 you can only install packages as root, so no more clicking on the RPM file on the website and getting Synfig to install, sadly.