I put something like this on my wife's iPhone and it works great. Well worth the investment and it really cuts down on the fingerprint smudges (the iPhone is flat out impossible to keep smudge free). I used this skin and bought one of the thin ruberized cases, and my 14 month old daughter has knocked it off tables on several occassions with not a scatch or even a blip of the screen. I have to admit for all it's lack of features, that thing is TOUGH and makes a great device for my wife. I also like the peace of mind that the thing can get thrown around her purse to her hearts content right beside that massive key ring and all I have to do is peel that thing off and it will look like new.
I wonder how well it would suit the Kaiser though since it has more moving parts. On the two occasions my daughter has knocked my 8125 off the coffee table, I have cringed. No damage, but on one occasion the battery door got knocked off, thus forcing a soft reset. Even with one of these covers, I am thinking the sliding keyboard and pop off battery cover will make it more prone to injury, even when it is in a decent case.
Bottom line, I'll be making sure my Kaiser is out of reach!!
AT&T Tilt: austinsnyc Big Storage ROM, MS VC 1.6, AEB+, Resco Suite, Tom Tom
Ghosts of phones past: Cingular 8125, Seimens SX66, iPaq 6315, Sony P900, Samsung SPH i300