Ben Ramsey has a new post talking about a feature that will become available in the PHP 5.5.x release series of the language - the array_column function. This function will extract all values from an array matching a given key.

My original patch for array_column() was written for PHP 5.2, but it sat around collecting dust for many years, until April of last year, when PHP moved to git and GitHub. That's when it became easy enough to apply the patch and send a pull request, which I did. [...] My goal for array_column() was simplicity. Many implement the functionality in different ways, and many call the function by other names (such as "pluck"), but I wanted to keep it simple and recognizable.

He includes an example of some sample data and how the function could be used to pull out the "last_name" field from each of the records and return just those as an array. If you're interested in seeing the original proposal and the RFC that was created for it, you can see it on the PHP wiki.