It appears that Lucid Lynx comes with PHP 5.3. Is there a convenient way to downgrade to the latest 5.2x release?
Yes. Debian's (and Ubuntu's) apt package management is very powerful. All you need to do is add the sources for the previous releases packages, but tell ubuntu only to use them for PHP (and related dependencies) using a technique called "apt pinning". Instructions are here:
Another option is to install Zend Server Community Edition, which is a free PHP stack, obviously from Zend, that provides PHP 5.2 or 5.3 (choose at installation).
It comes with some nice extra's, such as Optimizer+ (a byte-code cache, similar to APC, that seriously speeds up script execution), Debugger and Profiler (must-haves), a Data Cache API (similar to memcached) and a nice GUI to manage the php.ini file and extensions.
All-in-all a nice package which I use on several servers.
Agreed - though I do turn off the optimiser, debugger & cache in preference to use APC, Xdebug and Memcached May 11, 2010 at 21:19
Instruction also here http://mrkandy.wordpress.com/2010/04/16/install-php-5-2-x-in-ubuntu-10-04-lucid/