Is there going to be an API to access the front camera for the iphone 4? Will 3rd party applications be able to utilize the front facing camera for photos or other features?
The people who can likely answer this are likely under NDA.
In the developer keynote, there was a slide that said developers now have access to the camera data. I wouldn't expect Apple to block access to one of the cameras.
If you read what people who have played with the device say then no API is needed: you display the standard image picker and there is a UI for the user to choose which camera they are using. So all apps get this for free. I imagine that there will be a way to tell the picker which camera you want to be using when it first displays...