UPDATED in Ubuntu 12.04 (Precise Pangolin) and PHP 5.4 (again) (May 22nd 2012).
I was looking forward to trying out some of the new features in PHP 5.4 when I upgraded to Ubuntu 12.04 this morning. Unfortunately, Ubuntu decided to stick with 5.3 for this release.
There is upgrade path available though via a PPA (Personal Package Archive) from Ondřej Surý at https://launchpad.net/~ondrej/+archive/php5.
I’ve just installed it and it’s working fine with Apache:
$ php -v
PHP 5.4.0-3~precise+4 (cli) (built: Mar 27 2012 08:50:50)
Copyright (c) 1997-2012 The PHP Group
Zend Engine v2.4.0, Copyright (c) 1998-2012 Zend Technologies