SoundHound's 'Add to Spotify' button creates playlists from songs you have identified
Create a Spotify playlist with the iOS version of SoundHound
Previously, songs identified on SoundHound could be played on Spotify, but now a playlist can be created for Spotify while still inside SoundHound. Songs can be automatically added to a Spotify playlist, or added when the "Add to Spotify" button is pressed. Users can listen to the full track, add it to other playlists or share it with other Spotify users via a social network. Those SoundHound users without a free or premium Spotify account will be prompted to open one.
As for SoundHound users with Android, Windows Phone or BlackBerry 10, there is no word on when this feature will be made available to those platforms.
source: SoundHound via TheVerge, Engadget