For 7-inch tablets to succeed, though, they will have to be able to get past the barrier of software compatibility. I see this time and again: Device innovation outpaces mobile app development which, in turn, has led to less than optimal presentation of apps on different screen sizes.

The app presentation in question has to do with layout and graphics resolution. Apple is ahead for now on this issue because its operating system, iOS, has just two screens to support (those of the iPhone/iPod and the iPad). That's also true for RIM's BlackBerry PlayBook tablet.

But HP's WebOS may have scaling issues (we've seen a bit of this already while using apps designed for a WebOS phone on the big screen of the TouchPad tablet, where apps designed for the phone looked horribly pixellated when scaled to the tablet).

And Android-OS-based tablets are in chaos, with Android 2.1, 2.2, or 2.3 on many 7-inchers, and now Honeycomb 3.2 coming soon. How much of the chaos will be fixed by the introduction of Google's next-gen operating system, , remains to be seen when that OS arrives later this year.