You are quite correct - it is all about usability. The larger screen real estate and the rendering engine of the iPhone makes access to the Internet workable -

You are quite correct - it is all about usability. The larger screen real estate and the rendering engine of the iPhone makes access to the Internet workable - plus the Apple deal with the network providers ensures that Apple phone users can reach the Internet (and thus, in this instance, Google) unimpeded. I think this is a clear indicator of the key role that phone based (or perhaps more properly phone accessible) applications will have into the future. There are still UI issues to be resolved (cut and paste on the iPhone not the least) to make hand held devices effective for general tasks but once the right balance has been achieved then phones will be the access point of choice for the vast majority.