This open-source driver developed by Broadcom uses the mac80211 stack native to the Linux kernel, supports the BCM4313, BCM43224, and BCM43225 chipsets and there is framework for supporting additional Broadcom chipsets within this driver in the future.
This new driver is named bcrm80211 and can currently be found in the Linux staging-next tree. Hopefully this Broadcom 802.11n Linux driver will be pulled into the Linux 2.6.37 kernel soon as its merge window is opened.
While this is wonderful to see, the driver is not yet complete and currently lacks support for 40MHz channels, power savings, AP support, IBSS, hardware-based encryption, LED support, and RFKILL. These features and other bug-fixes though should now come since Broadcom has finally learned to play with the open-source community. The new driver was pushed into staging-next via this Git commit.
The announcement of Broadcom's newfound Linux love can be found on the linux-wireless mailing list.