Street View Fun
This Street View demo map by Lim Chee Aun shows how to rotate a Google Map so that it faces the same direction as a Street View image. As you rotate the Street View in the demo the map rotates to face the same direction.
Rotating Map Demo
Chris Heilmann has created his own rotating map demo using CSS3 and jQuery.
Use the 'L' and 'R' keys to rotate the map. Also try and pan the map for a little added fun.
Chris has posted a brief explanation on his blog Wait Till I Come! that will help you if you would like to replicate this effect in your own maps.