/sbin/lspci -nnk | grep -i -A2 broad
12:00.0 Network controller : Broadcom Corporation BCM4313 802.11b/g/n Wireless LAN Controller [14e4:4727] (rev 01)
Subsystem: Dell Device [1028:0010]
13:00.0 Ethernet controller : Realtek Semiconductor Co., Ltd. RTL8111/8168B PCI Express Gigabit Ethernet controller [10ec:8168] (rev 03)
The driver brcm80211 supports BCM4313 and BCM43224, BCM43225, BCM4329 chips. The installation is straightforward.
1) Remove all WLAN configurations in NetworkManager.
2) Install kernel-firmware from a DVD with OpenSuse 11.4. That's is the file kernel-firmware-2.6.38-1.2.1.noarch.rpm. You should see after that all brcm80211 stuff under /lib/firmware/brcm
3) You will see Broadcom WLAN Controller with the device name wlan0 in Yast's Network Settings. All stuff is recognized well. Broadcom WLAN Controller needs a small configuration if you have a WLAN router (my one is FRITZ!Box Fon WLAN 7270). You should set default gateway and input WAP or WEP key for the authentication.
4) Reboot and enjoy the wireless LAN.
Edit: I was asked whether b43 drivers (for old BCM chips) should be removed. Yes, you can remove b43 and broadcom-wl-... drivers or do them blacklisted (see blacklist config files under /etc/modprobe.d/), so that they are not loaded at all.