Brian Swan has a quick new post to his blog for the PHP + Azure users out there on how to easily sort table entities by a timestamp through the Azure SDK for PHP. The timestamp is a property on the parent storage table class, so you don't need to create it in your entity, it's already there.
The problem boils down to sorting an array of objects by a timestamp property, so the information here is nothing that hasn't been done before. However, after spending some time looking for a way to use a filter in the Windows Azure SDK for PHP API, I didn't find one, so I'm hoping this post might save others some time. In the end, my solution simply uses the PHP array_multisort function.
Sample code is included - a basic class extending Microsoft_WindowsAzure_Storage_TableEntity, a fetch for the entity set of the contacts and using a custom "objSort" method that sorts based on the returned timestamp values from the object set.