Ujam works as follows. After login the Ujam website allows you to record or upload vocals, an instrument or other audio files (wav, aiff or mp3). When your song idea is uploaded to the server, Ujam analyses your song idea and puts the chords on a timeline. After that you choose the style, for example Techno or Brit Pop. Then Ujam creates the song in the chosen style. This video with the singer Alison Lewis shows how Ujam works:
Ujam is still under development, so the website can be unstable. This has advantages too, because you can still make suggestions on the forum. At this moment Ujam has no midi export for import into your favorite music software.