Last December Google released Google Maps 5.0 for Android which allowed us to rotate, zoom and tilt in and out of 3D maps. Whether you’re on the go or simply just browsing, seeing a 3D skyline spring up in New York, Zurich, Milan, and other cities is extremely ideal. Google are currently working on more major cities as we speak so if you’re city is not yet available to view in this mode do not be put off as I am sure it is in the pipeline.
Google have been adding more cities and you will now find that that 3D buildings are available to view in London, Paris, Barcelona, Stockholm, Singapore, Lisbon, Boulder and 11 major cities in South Africa.

Running on Android 2.0 or higher? then simply open Google Maps on your Smartphone and zoom into your chosen city and view in 3D!
SOURCE: Google Mobile Blog