I can hear the thuds on the floor as the "I just don't get it" brigade become overloaded by Facebook's announcement that it is extending the ways in which applications can integrate with their mobile platform. They are even opening up methods for sending SMSs. Facebook has been a runaway success as has text messaging. Up to now if you write an application for Facebook you lose members of your audience when they.. well, go out. Now you can interact with them wherever they are.
The SMS aspect could be useful too. On a mobile phone network you can receive an SMS message even when the signal is not good enough to make a voice call or browse the web. So a user will still be able to interact with an application (including querying the application by text message) from some quite obscure places.
It will be interesting to see how this develops. Providing a relatively open platform to provide applications though a trusted site might persuade more people to use their mobile phones for web surfing, and will hopefully be a great boost to innovation in this area.