I just put together this API in PHP for retrieving the online status of a Google Talk user. It’s based on the Google Talk badge but allows for server-side access to a user’s status.
Why would someone need such a thing? Well, let’s say they wanted to create a badge controller which checks a number of users to see if they’re online, and when it finds one, it displays the badge for that user. This controller can then serve as a live help module to place on a web site to allow site visitors to talk with any available representative. If no rep is available, the controller can disappear seamlessly, or display a link to a contact form or help/faqs pages.
Download checkSkype.class.php, a modified phpclasses file for checking a Skype user’s status. Skype is, to date, much more friendly for allowing APIs to access a user’s status.