Mercedes has been working on one and I believe showed one off at a car show or two. There are also a few cities in the US (and probably abroad) that are already using diesel powered hybrids. Try searching on google, you'll find a few.

here's a starting point

http://www.wired.com/news/autotech/0,2554,66949,00.html

I don't rate Wired when it comes to assessing fuel technologies, but it's got a few good tidbits in this article.

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1982 300TD 210K miles ("The Replacement" aka "The Anvil") - SOLD
1979 300SD 245K miles (never ending project)
2007 Pinarello F3:13
1995 Ducati 916 (SOLD, sniff)
1999 Ducati 900SSie (SOLD)