I really wanted a diesel and had been saving for a Grand Cherokee CRD, but the price of the 2007 is simply too much to justify the cost, and they are not available yet anyway.
I test drove a Liberty CRD last year and thought the engine was quite nice. The Liberty was cramped though, and I had heard a lot about problems with the EGR valves failing (costly item) and the crankcase ventilation system (CCV) gradually filling with oil because they did not design a proper filter for it. The lack of ULSD fuel probably was probably an issue too, since the VM engine apparently was really designed to use that fuel.
After driving the JK this year (and losing my JGC to a deer, which forced me to look for a new Jeep), I decided to order a 2007 JK Unlimited and plan on trading for a JK diesel once one has been out for at least a year or two. I'll be very interested in hearing how the 3.0L diesel performs in the new JGC's. I'm crossing my fingers and hoping there will be a decent diesel/tranny combination out in service for the JK by 2010. Biodiesel is the way to go in my opinion, and if the engine is designed right you still should get 200-300k miles out of it, even without the extra sulfur for lubricity (wonder if that is true for the 18 wheeler power plants out there now, going to ULSD? Another thing to watch for re diesel engine reliability/design I guess).
Anyway, I think D-C has a hit with the JK and they will offer a reliable diesel in the US someday (I wonder if the Daimler will still be there, of course). When that happens, I'll be thinking hard about either a trade or getting a second Jeep!