No, I’m not talking about my month-old HTC Desire Z.

I’m thinking of the new (and as yet unreleased) Motorola Atrix 4G.  Besides the dual-core silicon running under the hood – something that seems destined for all new high-end smartphones btw – the big news for the Atrix is the “webtop” app and docking abilities. Said abilities allow your little pocket burner split personalities, shedding its smartphone skin for a laptop visage or home multimedia center duty.

Certainly sounds cool, and brings new weight to the notion of a converged device. But the problem, as I see it, is that you can’t deal with all of these persona at the same time.

Here’s the skinny.

Right now I’m in Starbucks, and I was thinking to myself; “Man, it would be nice if I had my laptop with me.” Then I thought to myself; “Hey, if I had a Moto Atrix I’d be set!”

But I wouldn’t.

For the Atrix to be useful in this situation, I’d need the laptop dock. And if I’m going to carry the dock around with me, then how is that any better or worse than carrying my netbook with me? Without the laptop dock the Atrix is no more useable than my Z.

Wait, it gets worse.

With the laptop dock, and running the webtop app, I can’t do cool things like run a Java-based SSL tunneling client to connect to my home network. And that’s just one example. What about running a development IDE?

Sure, you can run Google Docs and do any number of other cool web-based thingamijigs. But a real laptop the Atrix is not.  It’s somewhere between a netbook and a tablet, in my humble estimation.

Then there’s the multimedia dock. And again, you’ve got to look at it for what it really is. Today’s tech push into your living room is all about net-connectedness. Watch Netflix on your TV. Watch Hulu. Do it fullscreen, in full HD, at 24 to 30 FPS.

Now, you may be able to get close to some of that using the Atrix’s web-browser in webtop mode, but the jury’s still out on fullscreen performance. And that’s crucial.

You can get the fullscreen, full HD, full FPS experience using the media player in webtop mode, but my research leads me to believe that that’s for local content only. No Hulu, no Netflix, no vids from your Windows Home Server or other DLNA-graced devices.

So again – what’s the point?

Don’t get me wrong; the Atrix is a great example of pushing the boundaries when it comes to smartphone design and use. But I fear that the implementation, while abounding in gee-whiziness, doesn’t really give us anything that we can’t already get (better) by carrying the same amount of hardware. Factor in efforts like Firefox’s Weave or Opera’s Link, and the lines between your desktop and your mobile are already being blurred (I’m thinking along the lines of the vaunted Connected Client effort).

I have no doubt that people will drop large dollar bills to get an Atrix and its assorted docks. But I truly wonder if their digital lifestyles will be improved as a result of it.