I do not speak according to my convictions, but based on facts.

I develop my comments:

On this link, http://wiki.maemo.org/Why_the_closed_packages, we can see 4 important reasons: keep exclusivity software, IPR & licensing issues, security and third party software.

Look closer:

Keep exclusivity software: this is not required to sell a great many unit. The HTC G1 is an evidence: 1 million of unit sell in USA with not-exclusive Operating Système (Android). And there exist other examples (but we will not list them all, it would take too much space). I'll add that the N900 is an exclusivity to himself: there is not exist a mobile PC equivalent today.

IPR & licensing issues: The risk of having patents on technologies include in Maemo 5 is the same for present proprietary elements than for elements already FOSS. For example: The kernel Linux may also contain elements protected by patents or licenses unauthorized. In addition, SCO seems saved to the bankrupt, so they could try attack Nokia for using the Linux kernel. Yet Nokia uses the Linux kernel in Maemo 5.

Security: Well, Nokia sees us like children? We are enough responsible to realize that if we change the power management and it no works, is our fault.

Third party software: Here is the only valid explanation. Whatever elements proprietary of third party, as Adobe Flash and other codecs, can be proposed to install to the user when they need it rather than include them. As in Ubuntu.

So in the end, 1/4 of explanations are valid.

There exist another valid explanation for some drivers: If understanding how functioning a driver can understand the functioning, and therefore facilitates the copying, of an electronic component, it may be understandable.

But that, they don't speak about this in this link.

So why Nokia make it so?

An error of Nokia?

Especially if Nokia releases its work under the GPL, the problem announced by Qgil turns into an advantage and everyone will gain benefits: Nokia, the community of Maemo, Maemo OS and Maemo OS users.

The G1 does have exclusive software on it. And Google is actively defending that exclusive software.

If you consider the N900 to be an N810+phone+updates, then I'd counter that the G1 is, in fact, pretty much in the same category. My G1 does almost everything that I used to do with my N810 ... plus it's a phone. The only things the N810 did, but that the G1 doesn't do (which pretty much boils down to "VNC viewer"), are "nice to haves" not "platform defining features".

(and, there is actually a VNC viewer, I just haven't gotten it to work for me)

The N900 is definitely NOT "in its own exclusive product category" (which is what you seem to be trying to say). There are definitely other devices in that same product space.

You forget the graphics hardware acceleration, the battery, and the GSM/GPRS which all have very valid reasons to be closed source.

Valid? Those are the pieces that, by being closed, won't let you replace the os.
If you don't have hardware acceleration, good power management, no gsm/gprs, you could as well buy a smartq instead of a nokia tablet.

There exists no valid reason for software to be closed source. So, no.

Other than "the person who wrote it, or sponsored the writing of it, wants it to be that way". Which is the only valid reason that needs to exist.

Even Open Moko had to pick hardware with only closed source driver because these were the only hardware which fitted the bill (IIRC power related).

In this case of Nokia they are hardware drivers which require closed source driver because else there would be no driver at all.

The choice is simple: either PowerVR driver or no hardware acceleration or no good graphics chip.

You can run another OS with Linux kernel just fine, or an OS which also supports this hardware.

if there is no valid reason whatsoever why on Earth does it exist?

Since you're quoting my post, I can't but help replying.

First of all, I didn't say anything about GSM/GPRS. In fact, the GSM modem is supposed to be accessible through the Phonet protocol, which has an open source driver in the mainline kernel. It is true that Maemo 5 uses a proprietary phone stack on top of that, but then there still is Ofono, which is in an experimental stage for the moment, but is already shaping up nicely.

Secondly, I disagree with your statement that there are valid reason to keep these components closed. The security argument is a invalid in my eyes. There should be no way to really destroy your battery from the software side in the first place. Make your batteries secure by themselves. Sure, you can still wear down the battery by incorrect charging or the user could replace it with a non-standard battery, but those are the kind of dangers you should expect when messing with such things.

The only valid reasons I see is brand protection, which is a real issue for companies such as Nokia. Third-party drivers are problematic, but this something where a big player like Nokia can help change things. Let's hope they continue to do so.

Invalid reasons, obviously. Because it's possible, and to some people's advantage. This is the same reason that other undesirable things (for example, most crimes) exist - if I could get away with it it would be to my advantage to mug you and steal your stuff; but that's hardly a valid reason for actually doing it.

The only "valid" security argument is that in most legislation it's illegal to be able to "tune" a radio to operate on other specs which will not necessarily comply with the frequency/power in which they are authorized to operate.

(But limitation should actually be enforced in the firmware!)