"For now, the Radio feature will not be available for U.S. users."

"The radio feature will eventually be available. However, I can't say exactly when that will be. Be reminded, that Spotify is not chiefly a radio service. The lack of a radio feature for the time being is a factor of licensing agreements with the rights holders but it will eventually be available.

So the lack of a radio feature in no way limits your ability to search for and play the song of your choice. Just to be clear, when the time comes, the absence of a radio feature will be available for free as well as Premium users, as it is not typically one of the main benefits of a Premium subscription. "

http://getsatisfaction.com/spotify/topics/radio_mode_missing...

If you go to an artist, you can also select an artist radio. Select the artist, and it's in the top tabs to the right.

Where would that be? Certainly not highlighted in the UI