by Soodalin on 14 Nov 2009 22:56
They are very different beasts.
Spotify is good for playing music you already know you like, Last.fm is good for finding new music that's similar to what you're already listening to, if that makes sense.
I use Spotify and link that to my Last.fm account so it captures what I'm listening to, then I'll look at Last.fm to recommend me some new music.