According to the ebuild, gst-plugins-neon-0.10.3 RDEPENDS on >=net-misc/neon-0.25.5, but it only works with =net-misc/neon-0.25.5.
These changes will enable it to work with neon-0.26, according to __tim:
No, wait. Please close this bug.
This report was based on an old ebuild. There is a patch now for it, called gst-plugins-neon-0.10.3-neonfix.patch, which reflects the current state of CVS.