The iPhone's OS X shares a lot of things in common with regular OS X, including stuff like Bonjour and SQLite (a light database). Other stuff like hardware accelerated OpenGL ES and positional audio are in there as well. Cocoa Touch APIs let people access the touch and accelerometer features.
"With the SDK, we're opening up the same tools we're using internally..." Keep in mind that a lot of this talk is going to be for developers.
Next up, SDK. Scott Forestall is coming out to show off the new apps in the SDK.