Let's start with an example: http://weloveastrid.com/
As you can see, their promotional screenshots are surrounded by a picture of an actual hardware - Nexus One in this case. Is the usage, for purely commercial reasons, of those pictures of existing hardware legal? Do I have to ask a manufacturer for permission?
In spirit of the question above, if you've got personal experience with that, how could I get hold of high quality pictures of Android phones?