Disclaimer as above

Given the approximate size of most forms of Penguin the most common use for this type of weapon would be Anti tank and Armour piercing rounds. The two major problems with using penguins as ammunition are of course the propulsion method and the fragility of the Penguin in it's natural state. To overcome these issues I propose the following:

Propulsion:

The air rifle type method may meet the non-explosive requirements of the device but the range of the weapon must surely suffer as a result. I suggest some sort of an electromagnetic rail gun setup. This of course would require the Penguin to be at least partially composed of metal. To this end might I suggest a Wolverine type procedure in which the Penguin's skeletal system would be strengthened using high strength metallic material. This would also aid with the second problem - armour piercing ability.

Projectile strength:

Obviously the weapon is useless against armour if the Penguin just makes a splat without causing any actual damage (although the enemy may be forced to employ high strength windscreen wipers on their tanks which may add to maintenance costs). As I have mentioned above the modified high tensile endoskeleton would help the Penguin pierce the armour of its target but this is just the beginning. Think titanium beak additions with barbed tips, sharpened wing mounted protrusions and explosives. That's right, explosives. Small incendiary devices could be inserted into the penguin (in a variety of ways) and be rigged to explode on impact. Clearly this would boost the usefulness of the Penguin in that several purpose built explosive designs could be fielded. Traditional munitions such as bunker busters and cluster bombs could be rendered obsolete while making the most of Earth's natural resources.

Other areas of development:

With a little research I am sure that many variations on the Penguin weapon can be designed and produced. One of the first versions off the production line would undoubtedly be the Penguin Torpedo. The sleek shape of the Penguin is perfectly suited to underwater applications and has the added benefit of being a natural sea creature and therefore harder to detect for an enemy expecting a more conventional torpedo. Of course speed would be an issue but could possibly be overcome by genetically breeding faster Penguins. The downside to the creation of such a weapon would be the undeniable terrorist threat. The thought of a stolen Anthrax carrying Penguin going off during a Sea world show is somewhat disturbing and could prove to be a very real threat should this weapon ever go into production.