This week, WordPress.com announced the addition of webhooks as a new feature for WordPress.com blogs. As a simple implementation of this new feature, I've built a webhook processor over on my site QwikTxt.com.
My webhook processor sends an SMS message to a registered user on my site any time that user's webhook gets called via a comment post on his/her WordPress.com site. My script at QwikTxt.com receives the data from the WordPress.com webhook, retrieves the user's cell phone data entered in their QwikTxt.com profile and sends a comment notification text message to that user.
QwikTxt.com is itself a WordPress.org powered site and a good example of extending WordPress beyond typical blogging applications.