If you don't see Spotify Apps you can grab it here: Spotify Apps Preview Version.
Here's the Spotify Apps info page.
I could find a link to upgrade. Can you?
Update from KabirH, of The Echo Nest, on twitter:
@stevegarfield The client auto-updates, I think it's slowly rolling out now. I haven't received it either, but the Preview client is stable.I wanted to get it today to try out the new Spotify Radio that lets you create radio stations like you can in Pandora.
New Spotify Interface
Spotify Radio Stations
Spotify Create a New Radio Station Page
You create a new Radio Station page based on an artist, jut like Pandora. Let's see how this works. :-)