Are you serious or are you just making fun of the concept? I wouldn't ever pay 4000$ for that kind of machine, but at the same time, I think it's an interesting concept. If you work hours and hours on your computer every day, I think a big screen is neat. And being able to just fold and go is a big plus too.
You can get an iLugger for the iMac, but as I found out the hard way, some airlines enforce the weight limit very strictly, so I couldn't take my beloved 20-inch iMac with me to South Korea. IF - and I have no clue whether it's the case or not - the Dell weighs under the 10kg limit for carry-on luggage, then it's a decent fit for a certain class of people who want a very mobile desktop. I can toss my new Mini in my backpack, but the Dell 2405FPW screen I got for it will have to be shipped whenever I move, which is slightly annoying (and costs some $ too - something mobile workers would consider).
I would love to see a similar machine with a higher screen resolution though. I think Dell makes a 17-inch laptop with a 1920x1200 screen. (They do, right?) Why can't I get that same resolution on a 20-inch?!? The new Dell isn't a perfect machine, but it's a great concept... for some people.
Slightly off-topic, but I wish Apple offered a 20-inch iMac with a 1920x1200 screen. That'd be pretty cool!