Matt Cutts describes in his blog post why the German BMW site was banned from Google. I have to say, this is not very clear to me.
For one, I consider quite fair (if not a good practice) to show different content depending on client capabilities. If I had a site depending heavily on AJAX to present information, I would probably take some time to create a simpler version for those using text-based browsers (I myself use Lynx every now and then) or bots (like search engine bots), or other devices with limited capabilities, like PDAs.
I wouldn't consider this to be "cheating". It is obvious that I make my site more accessible to some users and I would think that I help search engines index my site. Would I have been punished by Google in this case? I hope not! Jeremy Zawodny writes:
Google is not some public utility or government service. They can do whatever they want with their search index: make it better, make it worse, censor it, randomize it, or sell printed copies on a street corner. Why? Because it's their index.
Of course it's their index. But if they want us to like their index, they have to be fair on us. For sure, I do not know the details of the bmw.de case. But if BMW did something similar to what I would have done, I think Google has not been fair with them.