Engadget posts the photo, which it says was sent in from an anonymous developer. As you can see, the GPS giant is mentioned on both the Maps Drop Pin page, as well as the Acknowledgement page.
Remember, Apple’s string of mapping company acquisitions involved mostly 3D/visual technology. It’s likely that it still needed help in the backend data/tiles area.
So, if you’re Apple, do you try to create an entire planet’s worth of maps from scratch? Or do you partner up with an experienced player like TomTom?