So what's the point of this?

There are lots of companies selling re-branded hardware from OEMs like you mentioned. However there are also lots of companies selling their own OEM brands that are more 'linux specific'.

System76 will probably provide my next laptop. Another popular one is ZaReason. There are others besides that. The 'dirty little secret' about laptops is that OEMs like Apple, Lenovo, Dell, and so on and so forth don't actually build their own systems.

The major laptop manufacturers (according to 2011 stats from wikipedia) are:
1. Compel (makes laptops for: Acer, Dell, Toshiba, Lenovo, HP)
2. Quanta (HP, Lenovo, Apple, Acer, Toshiba, Dell, Sony, Fujitsu, NEC)
3. Wistron (Acer spinoff) (Dell, Acer, Lenovo, HP)
4. Foxconn (Asus, Dell, HP, Apple)
5. Pegatron (Asus, Toshiba, Apple, Dell, Acer)
6. Inventec (Toshiba, HP, Lenovo)
7. Flextronics (HP)

So how it works, generally speaking, is that:

Chipset manufacturers produce reference and developer designs. They also produce drivers for target operating systems and such things.

The ODMs usually have very little software or developer experience, however they are experts in mass production. They copy the reference hardware designs from chipset guys, but tweak them to make them more suitable for mass production. The produce lots of 'generic laptops' that OEMs then pick from.

OEMs then are the public faces that we all know and love. Dell, Lenovo, Apple, etc etc. The provide Q/A, deal with end user's crap, marketing, and that sort of thing... just generally the stuff that nobody else wants to deal with. They pick out designs that the ODMs provide then depending on what they want to do they will get custom plastic, different keyboards, screens, and/or tweak the designs for branding purposes and to suit the target demographic. All the manufacturing that OEMs really do nowadays would be to slap in memory, hard drives, and install the OS.

Some ODMs sell direct to public, but it's not something they are interested in doing as it's not going to be profitable for them... OEMs are not only better at this sort of thing, but are their partners.

Here is Quanta:
http://www.quantatw.com/Quanta/english/product/qci_nb.aspx

So any OEM that works with Quanta will probably use one of those 3 models, rebranded and tweaked for particular demographic, and then sell it to you.

Sager was one company that I was interested in for a long time. This was back when it really was impossible to find Linux systems. This was back before Intel started working with Linux, pre-centrino days. This is because you could purchase laptops pretty much straight from the ODM they used without Windows pre-installed. This made them somewhat cheaper and I used to be much more anti-Microsoft then I am now. Things have changed since then, of course. Now you can find lots of Linux hardware.

But it's still useful to look what they do and sell as mearly a reference since they are open about their relationships. I don't recommend buying from them:
http://www.sagernotebook.com/index.php

They use Compal and Clevo. Clevo is the laptop manufacturer that makes gaming systems for Alienware and Voodoo PC among others.

The point of all of this is that if you choose to purchase from a Boutique Linux-specific OEM like System76 or Zareason (or any of the dozens of others) then you are going to get pretty much the same thing that you can get from any of the major OEMs like Dell or Lenovo. Everybody gets their stuff designed and built by the same guys. The difference is going to be a slightly higher price (smaller markets tend to do that) and, if the OEM is any good, vastly superior customer service for Linux users.

It's the Quality Assurance testing and customer support that really matters. The fact that somebody already went out and tried different systems to find the ones that work best, and then is able to test and improve drivers to the point were they work reliably is the difference. That is what really matters. This is the ONLY way you are going to get a Apple-like experience using Linux.

The downsides are less selection and somewhat higher prices, but not terribly.

Don't take any of this as recommendations on who you should purchase from as I am sure there are Linux OEMs that suck, but it is something to keep in mind. It really is MUCH MUCH MUCH easier to get good Linux hardware now then it ever was in the past.

It'll take a few years for tablets and smartphones (and similar mass comsumer 'embedded' devices) to catch up to laptops in terms of ODMs and OEMs and such, but it'll eventually happen. It will just take a couple more years, more or less. Things like EUFI and Microsoft paying money to have special relationships with hardware... embedded manufacturers like Nokia and whatnot are paranoid as hell and want to stop what happened to the PC market from happening to them, but all they can do is slow it down and it's expensive for them to fight progress.

They have already made the beta US-only so you may be correct.