Facebook's mobile platform has three parts, single sign-on, location API and deals. And they're focusing on doing software instead of making a phone.
Now you can use one login for all your mobile sites, meaning, log into Facebook, and then Facebook will handle your "logging in" to other sites through their APIs. There are also deals, which takes advantage of your Facebook single sign-on for authentication, as well as location APIs. So what's that mean? You can see where your friends are, write and publish check-ins, and search for relevant places. Mostly only cool for developers, but it allows apps to do more things. [Facebook]