ThinkPad 11b/g/n Wireless LAN Mini-PCI Express Adapter II
This chip is currently not supported by any in-kernel driver. There are two options available, a Linux driver available for download from Realtek, or ndiswrapper. (Ubuntu 10.4 support it now).
The Realtek Linux driver for this chip can be downloaded from the Realtek website
More information about using the Realtek native driver in Ubuntu: 
Please note: use of this driver on Lenovo systems results in unpredictable fatal crashes on some systems! It's is *not* advised to choose this chipset.
* Connections randomly drop out after a few minutes (seems to be fixed in version 015) This problem has been observed with version 015 too. Realtek has been contacted about the problem. * When using WPA Enterprise, entire system will freeze after a few minutes, requiring reboot
More information on using the Windows drivers with Ndiswrapper can be found here:.