That's definitely what it looks like, but there is always a little option someplace else on there to create a Spotify login (which I did, cuz I'm one of the 5% of the population that doesn't have a FB account at all).

I like Groove Shark very much, and used to pimp it out, big time to my friends...Spotify just feels like a little more well honed version of GS to me...Like em both, but I go to Spotify for everything now.