The truth is that diesels have come a long way since they were popular in the '70s in the US and then forgotten when gas prices came down in the '80s. But their announced comeback is here. Offerings from Ford (the 4.4 liter V8 for the F-150), Audi (3.0-liter V6 for the Q7 and the A4), BMW (3-series sedan, which we tried here), Cadillac ( 2.9-liter V6) and Toyota (the 2.2-liter I4 that could arrive from Europe).
The article makes special emphasis on how clean diesel technology has arrived, specially since, thanks to low-sulfur diesel introduction, catalyst treatments can now be introduced, either with urea injection (AdBlue, by German manufacturers) or via a more complex zero-maintenance system (by Toyota). While there might be additional systems, these two are the current ones available in the market.
There's also a special mention on the durability of diesel engines, which can clock 250,000 miles easy thanks to diesel's lower coefficient of friction, which lubricates when fueling the car ( biodiesel is claimed to be even better for that purpose, but note that biodiesel is never mentioned in the PM article).
To end the article, there is an interesting comparison between a Toyota Prius and a Polo Bluemotion (except that the prices weren't fair. A Prius costs from about 25,000 EUR in Germany, whereas the VW costs 16,300 EUR) stating that the small diesel was quite better in terms of mileage than the hybrid. Nevertheless, small diesels aren't arriving - yet - stateside.
[Source: Popular Mechanics (h/t to Matt for the tip), Auto-Preise for car prices in Germany]