Shared Playlists is currently a site only for Spotify users to share playlists. If you register it will be able to look at your last.fm profile and mash it up with Spotify.
Your Mashup not listed on ProgrammableWeb yet? Tell us about it and get listed.
PHP Class for Last.FM API
Python Audioscrobbler WS
Perl Library for Last.fm
Scrobbler Ruby for Last.fm
APIs, mashups and code. Because the world's your programmable oyster.
Executive Editor, ProgrammableWeb. Author, Map Scripting 101. Lover, APIs.