I just came across this Wikipedia entry:
https://secure.wikimedia.org/wikipedia/en/wiki/Comparison_of_open_source_wireless_drivers
It's really sad that only one manufacturer actually releases drivers under a
free license (Atheros's ath9k). The Openmoko Neo Freerunner phone also has an
Atheros chip for wireless connectivity which uses a GPL licensed driver
(AR6K). It's also sad that nearly all phones require quite a lot of non-free
drivers in order to function. For example, the Nexus S requires non-free
drivers for Bluetooth, GPS, wireless, graphics, GSM and NFC:
https://code.google.com/android/nexus/drivers.html
