I remembered hearing a while back that some adult diaper manufacturers wont include inner leakguards or waistbands because they are afraid of patent infringement. That got me curious as to what diaper patents there are out there. Google has a patent search engine that you can use to check out patents filed for diapers. Some interesting stuff there. Check it out sometime if you are bored.
Some interesting ones I found:
Entertaining Nose Clip Assembly for Diaper Changing ( link )
An early version of the disposable diaper ( link )
The (unfortunate) beginning of cloth like disposables ( link )
Please post any interesting ones you've found