Here's a video I took of my car idling in reference to this thread:

http://www.bimmer.info/forum/showthread.php?t=32207

You might have to turn the volume up a little.

When I drop it in gear you can hear the roughness better, and at the end about 1:15 or so right before I turn the car off you can hear it miss a couple time real good.

Now is this a normal idle for a 535?

http://www.youtube.com/watch?v=akFcRBpXUYA