For anyone else who is interested, there is an NDEF library on CodePlex that hint at some of the capabilities. Take a look at the source under NdefLibrary\NdefLibrary\Ndef. The two most interesting ones are the NdefLaunchAppRecord and NdefUriRecord. It looks like the former supports launching specific applications (using Windows GUID-style application ID's) with optional arguments and the latter supports arbitrary URI-based protocol launching.
The WinPhone8 SDK gives support for apps to register URI handlers, so this would likely be the way to register behaviors that various types of applications could theoretically handle down the road. In other words, instead of launching Nokia Drive with a street address, you could launch whatever app is registered with a navigate:// protocol handler (for example). If multiple apps installed on the device are setup to handle the same protocol, scanning the NFC tag would likely pop up a window asking you which app to launch. I have 20 tags on the way from Amazon and plan on hacking on this when they show up.