There are a couple of mp3 files that GStreamer plays at half-speed. I assume
there's some sort of frame damage to the files themselves, but they should still
be able to be played at normal speed. I'll upload two such songs; please try
them with something like mplayer or mpg321, and then with GStreamer. This was
reproduced on multiple systems.

It should be noted that all the systems upon which this was tested were FreeBSD
systems, under both 4-STABLE and 5-STABLE. However, I'm going to assume that
this is O/S independent and will mark this bug report as such.

Also, just to make sure that you have all possible information, both of these
songs were ripped from shoutcast streams using StationRipper
(www.stationripper.com).

I've put both songs in the following directory:
http://www.vectors.cx/gstaudio/