I got a chance to catch up with Fastmac at this year's Macworld. They had a booth set up where they were literally smashing an iPhone 4 with a hammer, right after they smashed some M&Ms! Why, you ask? Well they were showing off their Impact Gel. This is the gel that is inside of their cases and bags. It protects the crap out of whatever is inside.
M&Ms are small and break easy/smush, but when they are under this impact gel, that is about 1/4 of an inch thick, and smashed with a hammer, they don't break. The gel protects whatever item is inside, and doesn't let impact hit the iDevice or whatever is in there. Pretty neat!
FastMac | Product - Impact Shield for iPods, iPhones & Laptops