In this new article from PHPBuilder.com they take a look at namespaces, a feature added in the recently released 5.3 version of PHP and a simple example of their use.
With PHP5.3--which is in itself a precursor and somewhat of a teaser for PHP 6--comes something rather new to PHP: Namespaces. [...] However, even the widest scope implementation will eventually start running into issues with naming conventions. This is where namespaces really shines.
The tutorial talks about the need for backwards compatibility and shows a simple namespace definition (as well as some sub-namespaces to define things even more). They show how to add some simple code - a function - and something more complex - a class - into an "Example" namespace.