This radio is for GSM Galaxy Nexus devices running Android 4.0.3-based ROMs (IML74K).
I have uploaded the UGKL1 baseband, which has indeed appeared as a post in other threads, but has not received a concise thread of its own. As implied by the file name, it can be flashed with CWM.
In my testing, it improved my HSPA performance over UGKK7, but of course your mileage may vary.
Deciphering Samsung baseband codes:
UG = North America
XX = Europe
K = 2011 (11th letter of the alphabet)
L = December (12th letter of the alphabet)
# = Revision number
This means the radio is approximately one month newer than UGKK7, which breaks down to a North American radio from November, 2011.
//EDIT: Support confirmed for 850/1900/AWS via Rogers Canada and Mobilicity SIMs.
Samsung Galaxy Nexus i9250
Software: AOKP M5 / Lean Kernel 3.4.0exp4-180
Firmware: UGLC1 + PRIMELA03