Tristan asked me to review the November 2011 addenda for this Credit. There's a small text revision with significant ramifications.
"Exterior lighting power densities shall not exceed those specified in ANSI/ASHRAE/IESNA Standard 90.1-2007 with Addena 1 for the documented lighting zone."

There's a small typo, Addenda 1 is actually Addenda i.

Anyways. The intent for this change is that if these lighting zones (LZ) have different light levels then they should have different energy allowances. LZ2 needs less power then LZ3. And LZ3 needs less then LZ4.

Each site will have a small wattage allowance as a starter. 600W for LZ2 and 750W for LZ3. This is only intended to help small site that typically have a higher W/sf need.

Then add to that the W/sf values from a new Table 1. Example: 0.06 W/sf in LZ2 or 0.10 W/sf in LZ3 for parking lots and drives. This is a lot lower then the 0.15 W/sf we are used to. Here's the updated Table 1.
https://www.usgbc.org/ShowFile.aspx?DocumentID=10508

There is no mention of LZ0. I don't think it's that big of a deal because why are you even building in an area that would be classified as LZ0. It does sound like this LZ0 will be added to ASHRAE 90.1-2010 for when we all start using LEED 2012.

The 5% adder that we had been able to use is now gone.

This Addenda i is only applicable to this credit. It does not affect other credits like EAc1. At least not until LEED 2012.