Looks like Google is about to release an API for their Street View offering. No official announcement yet but a couple of sites have an example up:

http://virtualtourism.blogspot.com/2008/03/street-view-added-to-maps-api.html

I hope they expose some of the more interesting functionality and let you do things like display a static image based on lat/long/yaw/pitch/zoom.

--Callum.