Powerbooks have a motion sensor which protects the harddrive but as you can see it is useful for other things, too. Well, I do not have a Powerbook but my ThinkPad has a motion sensor as well. So I searched the internet for some code and found this blog entry. Two years ago this guy already wrote all the C# code you need if you want to built a similar feature for a ThinkPad. There is even a link in the comments which let you download a compiled version. I tried it and his demo worked perfectly. Unfortunately I have never programmed in C# before and don't have the time to build a prototype right now. But I am pretty sure that somebody will pick this up very soon and if not I will do it :)