Actually, there are a number of new diesel laws in effect and going into effect, and that seems to be some of the confusion in this thread.
First there is the new Federal emission standards that require different emission levels meet at different dates. These are requirements for the engine manufacturers. A big hurtle comes up in 2010, that has some of the big name manufacturers getting out of the diesel engine business.
Next, there is the CA smog law that starts in Jan. 2010 that requires diesel engines to get smogged much like cars here. It is a opacity test, a visual inspection of emissions equipment, and testing of the on-board computer. This law is targeted at 1998 and newer, 14,000 GVW and lighter diesel powered vehicles, so does not effect the deuce.
Next there are requirements to install particulate traps, repower or earlier retirement on heavy-duty diesel powered on-road owned by municapalities, and other local government agencies that have been in effect for several years. The state has been trying to push this off on everybody else for several years and will probably be successful eventually. Cities have not been able to buy diesel powered on-road vehicles since 2002.
There are also diesel idling restrictions, several heavy duty diesel emmisions testing programs, Off-road diesel programs, portable diesel programs and stationary diesel programs on the books.
I have to deal with this cr*p every day at work, and bottom line is that they seem to be targeting everything but our deuce. They are even doing studies on regulating fuel vapor emissions on gas lawn mowers as we speak.
For all you guys that think you are safe because you don't live in CA, quite a few other states are lining up to follow suite. NJ comes to mind first. The seminars that I attend, always have reps from other states taking notes, and of course, the first program I mentioned is a Federal requirement. What starts in CA, eventally infects everybody else, the "Assault Rifle" ban for instance.