OK people are being stupid here. There is nothing inherently dangerous about modifying genes, but the one place dangers can come in is if genes coding for allergenic proteins are spliced into it. That's why the DoA (should) clamp down on any attempts to splice, I dunno, peanut genes into grapefruit. (the one time it has been released without proper clearance has been mentioned in this thread, the papaya that is grown in Hawaii, which was a special case, (and it is hard to deny the positive effect of that crop on Hawaii). Other modifications like silencing genes would have no effect at all, because you can't be allergic to the absence of a protein.
But on the other hand, we can be absurd:
Anything of nutritional, health, or biological interest.
About most things in the store you could, probably, produce a volume of 300 pages with information of greater nutritional, health, or biological interest than the "GMO" (which is of no nutritional or health interest at all, and is misleading biologically). Would you suggest that every apple should be accompanied by a history of its breeding/selection/hybridisation, etc.?
As I said above, anything that makes people realise that agriculture isn't some mysterious black box process would help.
So, which other things would you like lables to be put about? Hybridization? (Undirected) chemical/radiological mutations? Selection for harmful (from the standpoint of the plant or animal) mutations? Make you proposal!
Simple answer: what consumers demand. If there was a huge demand (drummed up scaremongering or otherwise) for knowing some obscure facts about how the product is produced, then I fail to see why business should conceal these facts. As I said, I would quite like most products to be more "connected" with actual agriculture rather than (I dunno) animated dancing cows or whatever.
Pschology is a tricky thing, but most people are not reassured by an unseen didactic appeal to clever people; but are reassured when they themselves choose to ingest it. By continuing to oppose these laws, the industry is shooting itself in the foot and causing biotechnology great pains.
If a simpler solution is available, then choose that. The golden rice scenario is a good example: there is a problem (Vitamin A deficiency in the Thirld World) but it's worth investigating why that problem exists before throwing accusations back and forth to one another.
It is a simple and elegant solution. What is the problem?
Well in golden rice's case (moving beyond the fact that rice in general is a terrible staple crop) people seem to be under this assumption of the evangelical that this project is the only way to boost Vitamin A efficiency. The crazy thing is that nonmilled rice has Vitamin A in the bran, but it is only milled for Western tastes and to keep the fats going rancid during export. One could easily think - why not just leave proportion of brown rice for locals to eat? But for some reason there is only one solution for people who have already decided there is one solution, and that solution is the solution that is no way near close for commercial release (and the delay is not because of hippies).