According to a report from FlightGlobal, Diamond will announce at the next ILA show in Berlin the availability of its own engine, as an alternative to Thielert. The engine will also be made available to other manufacturers (a.k.a. Cessna for the C172 TDI).
This is not a new project, but it has certainly been accelerated by the recent financial problems by Thielert. I will keep an eye on that, and continue to keep you updated, also about other engines (Zoche, DeltaHawk, Mistral, …).
Read more about this topic in previous posts:
Cessna will not deliver C172 TDI in 2008

Vincent Lambercy is a Swiss private pilot now living in Germany. He holds a private pilot certificate with single-engine, multi-engine and instrument ratings and has logged more than 430 hours of flight.