Here’s another one: http://www.embeddedworks.net/wlan/oem_SMD_80211abg.html
AR6001XL, 20x20x3 SMT package.
I e-mailed for a datasheet, they were fairly quick about responding without any hassle.
Unfortunately, for some reason, I still haven’t heard from them… I’m eager to see what their appnotes and/or driver situation look like.
The only thing about their module is that it looks like it requires an external antenna. The power consumption is also over 300ma in TX mode, which is more than the rest of the device consumes at full power… 
But I guess if you’re transmitting, it’s probably going to take some power! 
I talked to embedded works this week. They only provide binary drivers (linux, windows) without a agreement between you and the chip manufacturer.
It’s an Atheros AR6001XL chip used on the embedded works module. That’s the same one used by the Silex SDIO card noted earlier in the thread. I’d imagine overall documentation situation on the internals is poor without an NDA - but again, it’s a standard SDIO interface so board layout shouldn’t be that complicated and the GPL driver I would think would work just fine (maybe tweaked for your specific SDIO interface on your microprocessor / SoC).
From the Silex web site: "# Compatible with Sourceforge (Linux) and Codeplex (WinCE) Open Source drivers "
Bottom line, I’m not sure you need that agreement in place. Note if you wanted to make extensive modifications to the GPL driver you might need that agreement in place to get documentation - I think the GPL driver was written using documentation only available under NDA IIRC.
I have a silly question… Since it’s just a SDIO interface, with the same chipset, I wonder if their drivers would work with the Silex SD card?
PredatorCoder:
I think the GPL driver was written using documentation only available under NDA IIRC.
The driver appears to be written by Atheros.
It is hosted at http://sourceforge.net/projects/sdio-linux/
There are various patches somewhere in the OpenMoko SVN http://svn.openmoko.org/
I think given this information I’ll opt to include an extra full-sized SD card slot for an Atheros-based SD WiFi module, rather than the footprint for the Embedded Works module, and see how this works out. It sounds like there’s about the same chance to get both to work, but the SD module is easily removable and potentially upgradable should another open module become available later on.
Thanks for pointing out the driver project on sourceforge, that was a great find!