Other members here have reported excessive run out in the actual hub bearing assembly which manifested itself as brake wobble (not general running wobble despite the whole wheel being out)
This run out could appear after a curbing or pothole crash.
The replacement hub assemblies are fairly cheap (£100/pair for top end SKF parts) from europarts etc and quick to change, with just 4 bolts holding them in.
Part 5 here
http://www.realoem.com/bmw/showparts...35&hg=31&fg=10