This is the post I looked and fixed my wifi on 10.7.2:
InsanelyMac Protégé on insanelymac
Cheers to the guy who post that, all credit go to the person.
To simplify the steps:
1. Remove IO80211Family.kext from S/L/E
2. Replace with IO80211Family.kext from the zip file here. IO80211Family.kext.zip
3. run Kext Utility from Utilities
Hope this will help all those who have problem with BCM41xx after upgrading to LION or latest version of LION.
Thank you.