From various news sites:
Researchers … have determined all octopuses, cuttlefish and some squid are venomous. The scientists …said their discovery indicates the octopus, cuttlefish and squid share a common, ancient venomous ancestor. Bryan Fry…said that while the blue-ringed octopus is the only octopus that’s dangerous to humans, the other species have been using their venom for predation, such as paralyzing a clam into opening its shell.
The media generally screws up good stories like this. They completely missed the point. The paper’s topic is not that virtually all cephalopods are toxic (I don’t really even know how they got that. They must have completely misunderstood the paper), but that there is high amount of conservation of what types of proteins are used between cephalopods and snakes in venoms, despite having independently evolved venom. The abstract of the paper can be found at http://www.ncbi.nlm.nih.gov/pubmed/19294452, and PZ does a good write up of the work at Pharyngula (http://scienceblogs.com/pharyngula/2…pod_venoms.php).
a related choice quote from PZ Myers about how evolution works:
evolution doesn’t just invent something brand new on the spot to fill a function — …existing proteins are repurposed to do a job. This is how evolution generally operates, taking what already exists and tinkering and reshaping it to better fulfill a useful function. Phospholipase A2, for instance, is a perfectly harmless and extremely useful non-venomous protein in many organisms — we non-toxic humans also make it. We use it as a regulatory signal to control the inflammation response to infection and injury — in moderation, it’s a good thing. What venomous animals can do, though, is inject us with an overdose of this regulator to send our local repair and recovery systems berserk, producing swelling that can incapacitate a tissue. Similarly, a peptidase is a useful enzyme for breaking down proteins in the digestive system…but a poisonous snake or cephalopod biting your hand can squirt it into the tissues, and now it’s being used to digest your muscles and connective tissue.