Providing Custom StreetView Panoramas
One of the most exciting developments for me in v3 of the Google Maps API is the support for custom Street Views.
With the new Google Maps API it is possible to seamlessly add your own panoramic images to Street View with links from Google's Street View imagery. For an example click on the Google Sydney link in this Street View map, Google Office Sydney.
This feature has been largely undocumented by Google, until now. Now Google have added instructions on how to create your own Street View to the Google Maps API v3 documentation. The documentation includes instructions on how to create your own custom panorama tiles and how to integrate your own panoramas with Street View.
Kerken Kijken met Street View
This Dutch website is the first example I've seen of someone making use of this new feature in the Google Maps API. Kerken Kijken have created seamless links to their own panoramic images in a map of Utrecht.
Kerken Kijken have a number of 360 degree panoramic images of the interiors of churches in Utrecht. They have created this Google Maps mashup to show the location of the panoramas and to integrate them with Street View.
The overall effect is extremely impressive.