I love portage above everything else, believe me, but the PHP package sucks. Although it compiles really well and is very easy to configure (hey, thanks Sebastian and all the other maintainers!), Gentoo seems to have an issue with enabling certain compiling options by default. If you don't set any of the USE flags (configuration options for compiling packages through Portage) for PHP, it will simply compile with --disable-all and is completly unusable.
He discovered this when he was working through an install to test something for eZ components and had to add in flags to the system just to get anything he could use. HE wonders why the most basic flags arean't included just by default, making for a much easier time for most users just needing something to get started with.