The OS and interface is quite similar to Google Chrome.

It basically is Google Chrome. It's an OS whose web browser is the entire thing. Even the login system is basically a Google account.

There would be some problems with downloading files from the internet as the internal file system is almost non-existent.

I thought they added a file manager Or maybe it's one of those things they're working on.

I think they're kinda cool, but they're EXTREMELY expensive for (pretty much) just a web browser.

You're paying for the hardware, not for the web browser. The OS is completely free (you can download it and use it on your current computer right now).

If it's just a tablet with a keyboard (pretty much ) I don't see any appeal to any customer...anything super epic about this besides it's 3 sec boot time and battery life?

In a world where you can do pretty much everything you do on a computer online (coding, gaming, chatting, etc.), and where you can be sure the things you can currently only do offline are being actively developed into webapps, I see it having a big consumer market in the near future.

What kind of architecture are these devices? 

They're intel devices, which means they run x86-64 chips, which appears to typically be either dual-core Atom processors or an intel celeron for the higher end. They also appear to have around 2GB of RAM for the lower end chromebooks and 4GB for the higher end ones. Other than that, the only real features they appear to have are networking stuff like bluetooth and 3g connectivity. The notable lack of mention of graphics hardware tells me that they almost certainly use integrated GPUs, a decision that makes a lot of sense. As for storage, the official website is silent, but wikipedia records them all as having 16GB SSDs. You aren't going to be storing those cute vacation pictures locally, no sir. Of course, the chromebook is a cloud device and thus most of the storage should be in the cloud, right? Not if you don't have money in your wallet, it isn't. The chromebook comes with a service called Google Drive, which gives you 5 GB free. A standard low-end laptop nowadays comes with somewhere between 500 and 800 GB of HDD storage. Google will give you 400GB for the low, low price of $19.99 a month. But oh no, we're not done yet. Remember that networking I mentioned? That 3g looks very nice, doesn't it? Too bad. Unless you go with one of Verizon's data plans, you're stuck with 100MB a month. If you want to stream a movie for a day, you can either cough up $9.99 for a one-day unlimited data plan or upgrade to one of the higher monthly plans for around $10 a GB.

One might make an argument that you can find wifi anywhere, but this is often false. As someone who drives around a decent amount, it's sometimes a source of frustration that there are no open wifi networks, so I end up having to use a phone to connect to the cell networks. With a regular laptop, of course, not being able to connect to the internet is really just an annoyance. There's plenty you can still do with a computer that doesn't require the internet. The chromebook makes most all of these impossible because all of your files are stored in the cloud that you're almost certainly paying for. As far as I can tell, this is a computer for people with more money than sense. Non-wifi connectivity is not an option for a computer that stores most of its files remotely. It is a necessity in any mobile situation, as laptops are expected to be in. Furthermore, the hardware is basically just good for browsing, and even that goal would be problematic on any of the web's numerous flash/javascript monstrosities.

If you use your computer only for light browsing in wifi hotspots with fast data speeds and don't mind paying more, then this is the computer for you. For everyone else, it's a bad idea.

EDIT: @Shmibs, the signed OS functionality can technically be disabled if you're willing to jump through some hoops to turn it off. But it's still stupid.

Chrome has its Native Client feature, though. I don't know much about it, but I'd imagine it would run into the same compatibility issues as a native program.

I like the 3 second bootup, but that's not enough to convince me. Even my commodore 64 from 1982 can do that.

3 seconds? That's how long my nspire takes when I open the document explorer

Have you seen the adverts for them on youtube?
They're really starting to annoy me, every time I watch something 

There have been ads on YouTube for a long time, and they're not specifically for Chromebooks. I've seen plenty of YouTube ads but not any for Chromebook yet.

AdSense is based on your browsing and searching history, so your profile might be more relevant to that than mine.