The night before leaving for a one week vacation, my usually faithful steed ('90 535i) played a nasty trick on me by jamming up the ignition. I'd had no prior problems with this, but I was in a shopping centre carpark ready to leave, when I found that the key would simply not turn.
Of course, I had read the thread a while back about this happening to other unfortunates. Anyways, I got a locksmith out to have a look. After 45 minutes of jiggering with it, he got the key to turn to a critical position, from where he was able to extract the cylinder. He found that the cylinder was fine, and that problem lay in the ignition switch itself.
To get me going, he forced the switch and something broke, but the ignition was then free, and I was able to drive the car. His advice was to get a new ignition switch, minus cylinder.
This proved a lot cheaper than getting a new switch + cylinder. The switch will cost me about $AUS240 ($US156), and I am hoping it will be fairly simple to install. The locksmith showed my how to remove the cylinder:)
Anyway, the switch, ex Germany, should arrive in about 3 weeks.