Some time ago I announced the start of a project to implement the Dirac codec in C. The project is called Schroedinger and we are currently starting get to a point where its becoming interesting for people to play with. If you check out current SVN it includes both a encoder and decoder plugin for GStreamer. David Schleef has also done the work to make sure it embeds properly in the Ogg container format.
There is still more work required however to finalize it. Its not 100% compliant to the Dirac specification, much more optimisation is needed and the library also needs to be properly set up with a public API. Current CVS also is hardcoded to do lossless encoding so the files are rather big.
I will report back on further progress as it happens. We have at least reached that first important milestone where its possible to transcode a file and play it back (on a fast computer) so visible progress should be easier to track from here on out.