How is this different from those glowing Chineese pigs or those neon tetras with unnatural colors that are illegal in California?
Those involved taking a gene that created a naturally created protein using naturally occurring amino acids and then injected them, frankenstein style into another animal. These take an artificially modified gene that uses an artificial amino acid to create worms that glow. Did you read TFS?
I've not followed what has happened with previous id releases. What have people done with them?
Mostly ported them to linux. Although there have been total conversions, such as tremulous, world of padman, and urban terror. I'm not aware of any non-game uses like medical imaging, 3d printer "print previews" or anything like that.
As opposed to... monohedral?
If at first you don't succeed, you are running about average.