I still can't believe it. Let me copy the official announcement verbatim.
Broadcom would like to announce the initial release of a fully-open Linux driver for it's latest generation of 11n chipsets. The driver, while still a work in progress, is released as full source and uses the native mac80211 stack. It supports multiple current chips (BCM4313, BCM43224, BCM43225) as well as providing a framework for supporting additional chips in the future, including mac80211-aware embedded chips.
The README and TODO files included with the sources provide more details about the current feature set, known issues, and plans for improving the driver.