Pete -
They've actually had WAG bags for several years now but they were optional up until (I think) last year. If memory serves, the privy at Outpost Camp was still open, but the one at Trail Camp wasn't. Or vice versa. And then the word was you couldn't use the privy for anything privacy so bring the WAG bag in to do your business and ... if anyone is really intent on the history of privys on Whitney they can peruse the Whitney Portal BB.
What isn't at all clear is - what is people's responsibility if they enter the Whitney Zone from the PCT (John Muir Trail)? They're getting different answers from different rangers depending upon where they enter the PCT/JMT because of differing jurisdictions within the USFS and then some enter via the National Park system (Seqouia, or Yosemite, or Kings as well as others). And even within the organization, like the USFS, they don't talk with each. One time I asked the ranagers at the Mt Shasta ranger station why they didn't use the very sophisticated, commercial WAG bags that Whitney used (Shasta uses a simple brown paper lunch bag, a piece of large pager with a circle (X? - can't remember - it's usually dark) and a Ziplock (regular, not the freezer) with some clay kitty litter). They were curious about what Whitney did, explaining that each jurisdiction makes up their solution. Then, if you go to Rainier, you get a blue bag. Yup, just a plain, plastic bag that's blue. Oh, and a twist tie.
Anyway, lots of big mountains now require that your pack out what you packed in - everything, except for urine and who knows if that will change. Whitney has the best bags (have had for years, even though they've changed vendors once or twice). Since the WAG bags aren't always needed, I keep the unused Whitney ones so that if I go to Shasta, Rainier, Hood, etc then I use the superior system. And it doesn't hurt to pack one or two gallon freezer quality ziplock/glad bags along to further encase the cargo and prevent odors.
This is probably more that most people want to know, but ... if you climb these big hills, then Leave no Trace has an extended meaning.