After a handful of apparent near incidents and incidents in the days following the new rules (at least one FTer reported second-hand that TSA forced passengers to give up spare camera batteries), there has been anecdotal evidence that TSA has been told to back off on enforcing the Li-ion battery rules.
The justification was that it's not TSA's job to enforce FAA/DOT rules. That's fine with me in this case. I'm thankful that for once they realized the disaster they would have created before it materialized; passengers were not going to willingly surrender $100-$200 hard-to-replace batteries to power tripping screeners the same way they sheepishly surrender water bottles, and there's no way the average checkpoint was going to be able to comprehend the nuances of the rules. There were in fact early reports of checkpoints "simplifying" the rules to be "one spare battery is allowed."
That said, I am on all trips fully prepared to explain volts, amp-hours, and watt-hours to TSA supervisors and have added a copy of the rules to the TSA file I carry on every trip. The rules essentially say that almost all consumer level laptop/camera/phone batteries are completely unrestricted as to quantity. The only (consumer level) exception would be the giant "universal" external laptop batteries, which would be limited to one per pax.