I'm also looking for a dab install on my 2010 model B class 180cdi, at present there is one firm called auto dab and depending on make and year of car they sell a unit which connects to current radio and dab feeds into it via RDS signal and works only from steering controls.
AutoDAB, DAB radio for your car have a look at their website it may help.
Thanks newbie, I have seen that solution, its quite cheap and cheerful but has some serious drawbacks compared to the MOST solution:
Sound Quality - MOST is full digital no FM modulated.
Integration - Autodab you need to tune to a particular FM frequency and then control it. MOST solution appears as a CD changer (Shows station names as well) and is hence easier to use.