Clay Loveless has some great news for those running RedHat-based versions of linux - PHP 5.3 can now be installed via yum.
Ever been frustrated that the latest this-or-that package for PHP is bogged down in Big Distro Packaging politics? I have been. That's why I've put together a deliberately-current-as-possible repository for PHP RPMs. The repository is currently i386-only, though I'll be adding x86_64 packages within the next week or so. Also, "regular" and "debug" builds are available for all packages, so that users may be more helpful in troubleshooting what issues they find.
Its not an official package, but if you're wanting to get it installed without the hassle that can come with compiling, you can grab the package get coding.