FPM uses libevent to manage connections and signals. Minimum required version is libevent-1.4.11.
In order to enable FPM in your PHP build you need to add --enable-fpm to your configure line.
There are several other FPM-specific configure options (all of them optional):
--with-libevent-dir - path to libevent install prefix.
--with-fpm-user - set FPM user (default - nobody).
--with-fpm-group - set FPM group (default - nobody).
Notice that the libevent requeriment has been dropped since php-5.3.4.
http://bugs.php.net/52501
http://bugs.php.net/53691
For Ubuntu 10.04 Lucid there is a backported ppa :
https://launchpad.net/~brianmercer/+archive/testing
An init startup script file can be found at :
./php-5.3.3/sapi/fpm/init.d.php-fpm
after successful compilation.