if you use apache2 with mpm-worker (USEFLAG threads and mpm-worker) php 4.4.0 is compiled as non-zts and mod_php is compiled as zts so the extension dirs are not the same and extensions shouldn't be compatible if you emerge dev-php/PECL-memcache-1.4 it is only build for the cli php and installed into the non-zts extension dir (should be the same for other extensions)
Please, use dev-php4/pecl-memcache for php4 and dev-php5/pecl-memcache for php5. Those are for the new php ebuilds in dev-lang/php. No plans to fix the old PECL ebuilds, they will be removed. Howto upgrade to dev-lang/php: http://svn.gnqs.org/projects/gentoo-php-overlay/file/docs/php-upgrading.html?format=raw