Thanks to Nathan Rennie-Waldock. you can have the latest PHP5 5.3.10 running in Ubuntu Oneiric, Natty, Maverick and Lucid.

PHP 5.3.10 fixes critical remote code execution vulnerability

The vulnerability was introduced by the fix for a hash collision denial-of-service flaw

Proof-of-concept code that exploits this vulnerability has already been published online

Nathan Rennie-Waldock Personal Package Archives (PPA) is located at https://launchpad.net/~nathan-renniewaldock/+archive/ppa

Just run as root the following to use PHP 5.3.10

sudo add-apt-repository ppa:nathan-renniewaldock/ppa
sudo apt-get update
sudo apt-get upgrade

Canonical should be a little bit ashamed to not deliver these security patches for the server edition! relying on individuals to provide the latest version of secure software is not promoting Linux in enterprise.