Here is something I haven't thought about in a long time.  As reported on SCOTUSblog, someone is suing Beretta for failing to warn that removing a magazine from a gun does not make it safe.  This all stems from a negligent discharge by a 13 year old boy playing with his friend.  He took out the gun, removed the magazine, proceeded to aim the gun at his friend, and then fired, killing him.  Well as most gun owners know, or at least should know, you should always keep a gun pointed in a safe direction.

How would a warning that "having a chambered round and removing the magazine doesn't make the gun safe" have changed the outcome? I doubt the two boys went through the instructions before deciding to play with the gun.  I'm sure the father, who was a Cook County sheriff’s deputy already knew the dangers and was taught safety.  This was a tragedy pure and simple. The gun manufacturer doesn't have the responsibility of teaching children gun safety, parent's do.

If it is right (which is not a claim I am making), stop and think about the cascading ramifications.  You could sue a car company for failing to mention that ramming your car into a brick wall at 60 mpg might cause personal injury.  You could sue Nike for failing to provide warnings about the dangers of walking with unlaced shoes.  You could sue Levi's if you managed to catch tender bits in your zipper while going commando.  You could sue Post for not making clear on their box that choking is a possible consequence of eating Grape Nuts. 

In a way, it's a comforting thought.  All I have to do is allow myself to be injured, threatened, or inconvenienced, then figure out which massive corporation will support me in a life of luxury from now until they go bankrupt.  I figure I'll have to launch a lawsuit every 3 years to ensure the continuation of an opulent lifestyle.

But the scary thing is, it's happening.  Ask McDonald's.  They were successfully sued for providing a customer hot coffee, and are in court over the health content of the food that people voluntarily bought. 

Gun manufacturers can, and have been, sued for "defective" devices, as any manufacturer can be. The difference, is that in gun cases many antis feel that even if the gun related injury/death is unrelated to any malfunction or defect, you shhould still be able to sue.
In fact, there is a Federal law, The Protection of Lawful Commerce in Arms Act of 2005, that specifically addresses this issue. The case at hand (per your link) is an attempt to revive an old case that was shot down at the Illinois Supreme Court level. The application for cert at SCOTUS is dependent on the current case (13 y/o sherriff's kid shooting another kid) being sufficiently different cases previously denied cert.
Personally, I don't think it has much chance of succeeding, but we'll have to see how things go.