Yesterday Google registered several variations of the domain "googlestreetview.com" -- normally I would think the feature would be months away, but given Where 2.0 starts on Tuesday, it will likely be available (or at least announced) by the end of the month. This functionality is likely in addition to the 3D buildings they are expected to announce at the same conference.
It's unclear what the service will actually look or function like, but we can look at Microsoft's "street view" preview for an idea. Windows Live Street View literally puts in in the drivers seat -- though you have to admit it's kinda crappy and appears to have been abandoned.
Google can definitely do better than that -- I am eagerly looking forward to see what they have in store.