So, I have finally found an answer to my question.
There are possibilities to access the hardware of the phone.
Here you can see the which features are supported:http://www.phonegap.com/features
A scribd user called enopen has published a paper, where he explains how this access is done.http://www.scribd.com/Enopen
Without a self programmed API you won't be able to access the hardware of your device.
But be careful, this is only needed when you need to access the hardware via the webbrowser. Otherwise I recommend to develop a native application where it is much easier to access the hardware via the Android API.