Hi, I read the article about the German BMW.de web site, very interessting. But I think that there are more using that way.

Have a look at http://72.14.207.104/search?q=cache:px86lTVZOlUJ:www.dotnetpro.de/articles/onlinearticle1846.aspx+dotnetpro+ajax&hl=de&gl=de&ct=clnk&cd=2. You will see there are some input controls and white text. If you open it with a browser (UserAgent not GoogleBot) it will not allow you to see the text, very interessting!!!

DotNetPro is a German magazine for Microsoft .NET developers.

I have heard of pages filled with white txt just for for SEO!!