No, there's not a single link that confirms it.
Here's an old (1991) Mobil 1 MSDS for Mobil 1
Ingredient: POLYALPHAOLEFINS
Ingredient Sequence Number: 01
Percent: >80%
NIOSH (RTECS) Number: 1001507PA
CAS Number:
68037-01-4
http://tranhaz-mat.sctc.edu/Oil_Filters/oil_msds.htm
Here's an MSDS for BreakFree CLP--it says that CAS 68037-01-4 is 53.4% of the weight of BreakFree.
http://www.wfrfire.com/msds/pdf/break.pdf
Ok, the part about the hurricanes disrupting the supply is harder to verify. I read that awhile back (maybe a year ago?) in a post from a person claiming to be retired from the oil industry. He was obviously very knowledgeable on the topic so I didn't ask for links. However, if you poke around you will be able to verify that Mobil 1 has been reformulated several times. The current Mobil 1 MSDS that I find don't show that the contain CAS 68037-01-4, but they also are much more vague, so it would be possible to argue that they're just getting more cagey about telling what's in their oil so there's less hue and cry when they reformulate.
PAO is a "Group IV" oil, what most folks refer to as a "pure synthetic oil". Mobil 1, by all accounts added Group III oils to their blend after losing a suit with another oil company over what could be called synthetic. Since the courts said that the blend could still be called synthetic oil I guess Mobil 1 decided it would be smart to save some money and go with a blend as well.
According to a couple of other sources, they changed again due to PAO shortages after the hurricane, but it's hard to get official & concrete information (such as from an MSDS) on the new formulation. If you're really interested, you could probably spend a week or so poking around and come up with something. If you do, post it here, I confess I wasn't motivated enough to do a really thorough research effort, maybe you can dig up some more information.