In a quick post to his blog, Nick Williams points out a very handy extension for PHP - Phar.

Today I discovered a very powerful addition to the PHP world. Phar is an archive extension for PHP that allows an entire PHP application to be packaged into a single file. It's basically PHP's answer to Java's .jar archive format. Don’t get excited yet, it gets better...

He mentions the reasons that make it "particularly handy" such as it being integrated into the next major PHP release (5.3) and that it makes deployment quick and easy. He includes a brief code snippet to show how a sample Phar archive could be created (via streams).