How are VW's repaired TDIs working out?

Local VW dealer just put a big ad in the paper for several different VW models with TDI. Am I right to assume these are not brand-new, but are cars that have undergone VW’s modifications to make them legal?

What did VW do to make their TDI cars legal? And how well do they work?

You’ll have more luck on a VW forum like VWVortex or TheSamba.

Here’s an explanation on what made then illegal in the 1st place