Just speculating here, but I presume killcrap is referring to the flexible coupling in the driveshaft. Boots are installed on the front axles.

I know these couplings can fail with higher mileage on an E53 and other models for example, but I am surprised that killcrap has seen so many fail on almost-new E70s.

__________________
2007 X3 3.0si, 6 MT, Premium, White

Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue