php 5.1.6 has been pushed into FC5 updates, php-eaccelerator needs to be rebuilt
I could have sworn I had already rebuilt it, but after checking right now, still no sign of a 5.1.6 compatible package. I'll take care of it now.
There had been a strange glitch in the build system (possibly due to the package version that depends on the php version), which has since been corrected.