I believe those moisture packets that ship with some plants use the same polymer that's in diapers (like my blueberry plants -- the instructions was to mix with water and dip the roots in it; it helped keep them moist till they got established.)
They also make a firefighting gel from it that's applied ahead of a wildfire to hopefully let it pass harmlessly. It's more expensive then the more common foam, but it lasts much longer with much more water in it. In theory it's supposed to break down in the sunlight afterwards.
Nope, not new...some gals have been doing it for several years. Just remember to either remove the plastic or poke holes in it...otherwise you can drown your plants. If you doubt...just take a panty liner (a CLEAN one) and dip it in a glass of water to see how much it absorbs.