Previously I mentioned the Marvell Libertas 8335 wireless chipset. In researching further the Marvell chipsets, it turns out that some of the Marvell drivers (though not the 8335) even have problems with Windows Vista.
The Ubuntu Linux community seems to have some nice documentation on using the Marvell 8335 chipset (the Linux driver is called mrv8k), including specific instructions for the TRENDnet TEW-421PC. The blog My Favorite Ubuntu has some nice instructions specifically about using the PM150NXT08 Wireless Adapter by NEXXT with Ubuntu Edgy.
The One Laptop Per Child (OLPC) project stirred up some serious controversy when the project went with the Marvell Libertas chipset, resulting in a very unhappy letter from Theo deRaadt. The Jem Report has an article that explains most all sides fairly well. In short, using the Marvell chipset required signing of an NDA, which means that the information thus learned cannot be used by the open source community to build or enhance drivers for this chipset.
It turns out also that the drivers for (some?) Marvell products require the use of proprietary firmware; thus, even with an open source driver the system still requires proprietary products to operate.
However, in spite of the fact that Marvell is the bane of the open source platform, it turns out that it seems to be the darling of the commercial builders. When Netgear chose the Marvell platform, Marvell released a press release about the fact and generally seemed to strut shamelessly. The press release was widely reported; here is the report as seen in the EETimes.
The Linley Group (who?) went so far as to state (in 2006) that Marvell’s chipsets were the best 802.11g chipsets in the market. This, of course, comes from Marvell (as reported by the Wireless Broadband Exchange Magazine here). If you want to see more awards and press releases ad nauseum from Marvell, check out their web site.
My current recommendation about the Marvell chipsets and those products designed around them: avoid them and go with the (perhaps older) better supported chipsets from other companies.
UNIX Administratosphere 
Totally agree.
There are some talks with Marvell because this chip is included in OLPC so MAYBE we might get an alternative driver or a little more support from Marvell.
Totally disagree.
i found this post by searching for a Linux driver for Marvell Libertas.
Marvell really has the best wireless chipsets (in terms of cost, power, package loss), and they want to protect their achievement by keeping their firmware proprietary. The whole discussion here is about to distribute or not the proprietary firmware (running on the chipset ARM processor, outside of the operating system).
It seems that the hardcore GNU license authors are really against anything that does not include the source code. They despise others right to defend their intellectual property, while they try to enforce their vision about IP: a world where IP is free and there are no patents but the consultancy very expensive.
A practical example is the removal from the CD Ubuntu/Debian distribution of the ndiswrapper. It is impossible to configure the wireless card without downloading something from the Internet. If Windows would require this, all Windows opponents would use this as an example of how Windows fails to understand what the user needs. I have three wireless network adapters, two USB and one PCI and none of them works in Linux without ndiswrapper. On the 64bit the adapters are making the system highly unstable, it cannot run more than 3 hours without a reboot.
I am sorry to say, but nobody has anything to gain from this endemic GNU license, neither the developers nor their users.
You rail against the GNU license – and yet, it was Theo deRaadt who called the Marvell Libertas chipset the most closed he’d seen. Theo doesn’t agree with the GPL license whatsoever – all of his material uses the BSD License, which is different.
There are a wide variety of chipset manufacturers that make their chip specifications available in order for people to write open source drivers for them. In fact, Marvell itself has recently opened other hardware up for open source development.
The reason products requiring NDIS wrapper are unstable is for that very reason: the specifications are secret and reliability cannot be assured since the specifications may be different than what is widely known.