Hello I too have a number of these.
I have security concerns with posting the only password, and it appears you can not modify the admin account without rewriting the whole image? so posting the password really makes these highly vulnerable! (I have people trying to modify these, with printers, to wallpaper, to pandora! and posting these passwords public with now way to modify them but rewriting the whole image,,well it worries me! (could you have pm'ed or messaged (after getting a serial then a callback to the orgs admin department?),,,(I may not buy more if they are less secure then a winxp machine on a domain,,,pleasse tighten up security,,,)
Check the available documentation for procedures to change the default password. Default passwords are widely-known, and have to be to allow people to set up their systems. "Security thru obscurity" - never talking about the default password - is not a realistic option. If you're still using any systems with a default password, it's on you to "tighten up" your security.