They've asked for a DMCA exception for:
Computer programs that enable the installation and execution of lawfully obtained software on a personal computing device, where circumvention is performed by or at the request of the device's owner.
So, for any device you buy, you can install GNU/Linux, or Rockbox, or OpenWRT, or Sugar, OpenMoko, etc.
Their argument is based on recognising the value of the jailbreak-exemption which was granted in 2009, and saying that SFLC's suggested exemtion is what's needed in 2012 and beyond to achieve that same sort of goal.
There's no dense legalese in the document. It's a readable set of arguments with numbers and examples to back them up.