I don't think Optimizer is part of the PHP core, I just think it's been dropped in favor of making it a feature of Zend Server (which is a pre-compiled version provided by Zend that goes far beyond simply compiling PHP). Either way, I wouldn't worry about it.
I cleaned my cache but eaccelerator still doesn't show up for 5.3
# yum install php-eaccelerator
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
* addons: mirror.icpl.org
* atomic: www3.atomicorp.com
* atomic-testing: www3.atomicorp.com
* base: ftp.usf.edu
* extras: mirror.web-ster.com
* rpmforge: apt.sw.be
* updates: mirror.its.uidaho.edu
Setting up Install Process
Resolving Dependencies
--> Running transaction check
---> Package php-eaccelerator.x86_64 1:5.2.14_0.9.6-4.el5.art set to be updated
--> Processing Dependency: php = 5.2.14 for package: php-eaccelerator
--> Running transaction check
---> Package php.i386 0:5.2.14-2.el5.art set to be updated
--> Processing Dependency: php-cli = 5.2.14-2.el5.art for package: php
--> Processing Dependency: php-common = 5.2.14-2.el5.art for package: php
--> Running transaction check
---> Package php-cli.i386 0:5.2.14-2.el5.art set to be updated
---> Package php-common.i386 0:5.2.14-2.el5.art set to be updated
--> Finished Dependency Resolution
Dependencies Resolved
==============================================================================================================================
Package Arch Version Repository Size
==============================================================================================================================
Installing:
php-eaccelerator x86_64 1:5.2.14_0.9.6-4.el5.art atomic 113 k
Installing for dependencies:
php i386 5.2.14-2.el5.art atomic 1.2 M
php-cli i386 5.2.14-2.el5.art atomic 2.4 M
php-common i386 5.2.14-2.el5.art atomic 278 k
Transaction Summary
==============================================================================================================================
Install 4 Package(s)
Upgrade 0 Package(s)
Total download size: 4.1 M
If I disable atomic it tries to install the 5.1 version in rpmforge.
As for libedit, the problem could be in the 32 bit version. I hadn't paid close attention before
php-cli-5.3.3-2.0.el5.art.i386 from atomic-testing has depsolving problems
--> Missing Dependency: libedit.so.0 is needed by package php-cli-5.3.3-2.0.el5.art.i386 (atomic-testing)
I removed all the 32 bit versions and had no further problems with libedit.