I first saw this on CNN last Saturday while waiting at the car dealership while the TARDIS was undergoing its yearly inspection: A company called MJ Safety Solutions is hawking bulletproof backpacks for kids and travelers to protect them in the event that someone draws a firearm and starts shooting at people. The backpacks weigh about 1.25 pounds and are meant to either stop the wearer from being shot in the back, or they can be used to provide a measure of protection to the head and torso if the backpack is removed and used as a shield. A little digging on the CNN website revealed the video clip they showed on television that I mentioned earlier. The bulletproof inserts of the backpacks were designed with school shootings in mind; research showed that, by and large, 9mm pistols firing hollowpoint bullets were fired, so that's what the inserts are best at stopping. The video shows a backpack taking a couple of rounds at close range and stopping the bullets successfully. There's just one thing about bulletproof gear, though: Even though the bullet can't perform its intended job (which is to burrow into the target and expand or fracture into shrapnel, thus imparting its kinetic energy), it will instead dump its kinetic energy into the barrier that stopped it.
In other words, if the barrier isn't securely fastened to something heavy (like the ground), both the barrier and the wielder are going to go flying and possibly also break a couple of bones because the bulletproof barrier is going to slam into the person wearing or holding it at speed.
You know, come to think of it, this is the sort of thing that you're likely to find in a game like Cybergeneration: Kids carrying bulletproof armor disguised as school gear. As for whether or not this product will take off, neither RPGs nor I can reliably predict, though the price tag ($175us) is reasonable for a middle class family afraid of losing their children in another Columbine-style massacre.
Another factor to take into account is legality: It isn't always easy to determine whether or not it's legal in your state of residence to own or wear bullet proof armor. After some asking around and digging, this is probably the best source for the information at this time, short of phoning your local or state government and social engineering your way to someone who is actually qualified to answer this question (a much more difficult task than it sounds - just ask anyone who's tried to find out if they could legally have encryption software on a laptop headed out of the country in the late 90's and early 00's). So far as is known, it's legal to own and wear body armor in any state but Connecticut unless you've been convicted of a felony in the past. Of course, it's a felony to wear body armor while you're committing a crime.