The definition there is: The Internet is the Internet, and sites should run well on all devices. Optimization should be based on CSS and device detection, but should not change site function or content beyond the necessary.

I couldn’t have said it better myself. Dan, as you pointed out, pinppl exploits the BB browser’s PIN number detection capability. And in terms of device detection, pinppl easily detects the BlackBerry series number, and it uses this to display, and not display information where absolutely necessary. (For instance, the BlackBerry browser cannot handle file uploads, so pinppl will not display this form element.)

The underlying XHTML markup remains unchanged regardless of which Web browser is being used, be it on the BlackBerry, or PC.

This is the beauty of well-structured markup, independent of visual elements – CSS handles that end, and does so wonderfully.

There are few mobile devices now that cannot handle basic XHTML. The reason for this being that users want to use, what they consider the “real” Internet – not mobile specific sites, of which there are very few in comparison.