So your only proof that they violate the GPL2 is that it does Wi-Fi?
I'm no expert in GPL2 of embedded Linux, but I will guess the Wi-Fi stuff can work on embedded Linux, and if you want the source code for that you can probably get it at the site that distributes the version of Linux that is the basis of this device, maybe try look what source code is available on Montavista, or QT Linux project sites, or maybe check out if Texas Instruments has some GPL2 source codes for the kind of Linux that works best with the DaVinci chip. Probably that every modification and suggestion that Archos does to that Linux core, probably in collaboration with Texas Instruments and other technological partners, probably that the source-code is available there. But for sure you cannot take that source code, modify it and install it on the 604 Wi-Fi, since the 604 Wi-Fi probably has all sorts of un-crackable 128bit or more firmware encryption algorithms that make it impossible for anyone else than Archos to produce a firmware update file that will install without modifying the actual hardware, with a modchip or something, and that makes it useless for most users.
Now again, I am sure Archos can put as much proprietary stuff they want on top of that Linux, that proprietary stuff is probably drivers, multimedia encode decode functions, overlay features and more proprietary hardware stuff including the hardware that makes DRM, Macrovision, Plug-ins, managment of codec Licences and more.
Instead of doing one more Linux PDA-like device, like the PMA430, which was not a commercial success, they decided instead to make a touch-screen and Wi-Fi device with the same Multimedia features, respect of copy-protection, respect of macrovision on analog signals, respect of on-demand Licences for codecs and more which is standard for the fourth generation of Archos devices.
With regards for more cool touch-screen and Wi-Fi features, sure it is fantastic, but the strategy is not this time on counting on the open source and SDK Linux embedded developpers community to add stuff, because that didn't work great with the PMA, this time Archos decided to be the one responsible for adding features, and I hope that they can make it using an auto-update function so that most users who have bought the device will know about the new features when they are available (a little alert icon showing as soon as a connection to the internet is activated "New firmware update available with new features, connect charger or usb cable and click here to download and install it") - an auto-feature-add auto-firmware-update feature like this one, and if Archos can sell a lot of 604 Wi-Fi worldwide this Christmas, this will provide the user base with reuirement for a combined after-sale customer firmware support that Archos will be able to provide new important features that most users will be able to auto-upgrade their device to have, thus continuously improve the value of the device..
And the features most people want are multimedia-centric, and really Ip-centric which Archos software engineers together with Archos software partners really are the only ones who can really program in a reasonable time (to have some fully working updates ready within months), not PDA-centric like most of the open-source Zaurus software is (office and calendar type software and the likes which not many people really need and want).. If you are a very talented embedded Linux programmer and you would like to contribute some features to this device, I suggest you rather try to apply for a job with Archos, or look at the work of the people at http://openpma.org
for the old device, cause I'd say Archos probably won't go with the open-source strategy until that the audio and video industry really drops the idea of wanting to copy-protect content, and until regulation stops requirements for respect of Macrovision analog signals, and until open-source codecs become the main standard or that regulation changes the way codecs have to respect some certain licensing. I guess this change of the industry and the international digital laws won't happen for a year or so at least. For now, proprietary software for this type of device is the only way that works financially and legally.