Just out of curiosity, why is it you like GStreamer over - say - Helix or Xine?
I've been happy with Xine on my upgraded Amarok (1.4 b1) and really wasn't unhappy with Helix before.
To tell the truth... I'm not really sure :-) Helix worked fine for me. I only stopped using Helix because the latest builds of Amarok 1.4 on apt were not built with Helix support enabled. I tried using Xine and it would not play MP3s. A friend encountered the exact same thing. Helix was not included... and Xine wouldn't work with MP3s (so I know it wasn't just me). GStreamer worked... after I installed mad and gstreamer-mad, and then ran the gst updater. Personally... I'd be fine sticking with Helix if it was included in the Guru (or other) builds of Amarok. C