There's a ridiculous amount of misinformation spreading online about the new maps in iOS 6, compounded by incorrect press reports, vague statements by Apple, and the developer NDAs. I'm even guilty of spreading it myself, based on reports I'd seen on the blogs.
Using information provided to me by an anonymous Apple developer, I've pieced together the facts. Keep in mind that iOS 6 is still prerelease beta, and Apple may change anything at any point. Everything below is based entirely on the existing beta software and documentation that Apple's provided to developers.
Were walking directions removed in iOS 6? Some press reports have stated that walking directions are removed from iOS 6. This is completely false, and walking directions are still in iOS 6. Here's a screenshot of walking directions in iOS 6, courtesy of Philip Bump.
Were biking directions removed? Bike directions have never been available on the iPhone, and still won't be in iOS 6.
Were public transit directions removed? As of this beta, inline public transit directions are gone from the Maps application in iOS 6. Clicking the public transit button will display a list of third-party apps that support routing in the defined map area, and will launch the app when clicked. Here's the current screen in the beta, with no apps registered.
By release, this blank screen will be populated with a default list of appropriate apps from the App Store. The documentation states, "If the user's device does not currently contain any routing apps, Maps refers the user to apps on the App Store that do."
What about the new Transit APIs? The new Transit APIs, referred to by Scott Forstall at 108:58 in Monday's keynote, allow developers to register their app as a directions provider for routing directions for a particular set of coordinates. It will then be displayed in the list of available third-party apps for transit. Clicking a transit app launches that app, passing the start and end values to the app. Contrary to other analysis, transit routes can't be displayed inline from the Maps app.
How do the Transit APIs work? Apps can enable directions support by setting the type of directions they support, a geoJSON file specifying the map regions they support, and uploading it to iTunes Connect. Developers can specify a category (Car, Bus, Train, Subway, Streetcar, Plane, Bike, Ferry, Taxi, Pedestrian, Other).
Directions requests from Maps are handled by a special URL. From the documentation: "When the user asks the Maps app for directions and chooses your app, Maps creates a URL with the start and end points and asks your app to open it." From there, the app can "compute and display the route using your custom routing technology."
Of course, any of this may change before release. But, for the moment, the APIs simply don't support inline transit routes from within the Maps app.
Are Street View photos removed? Yes, these were also provided by Google.
Why is Apple doing this? Do they hate public transit?! Of course not. Transit directions aren't in iOS 6 because Apple replaced Google's maps with their own solution, which didn't include access to transit data. Maintaining transit feeds and keeping it up-to-date for hundreds of cities was presumably too difficult to attempt for this first release, so they decided to outsource it to third-party apps.
Is Google going to release a Maps app for iOS? We don't know. Google hasn't announced any plans for a native Google Maps for iPhone. And there's a big unknown: if they developed it, would Apple approve it?
Hope that helps. Hit me up with any more questions, or if you have internal information, I'll happily honor your anonymity.