From the Toys section:
ThinkGeek.com offers this Case with Flip-Out Keyboard for iPhone 4 or 3GS, model no. TK-421, for $49.99. Coupon code “NEXTORDER” cuts it to $39.99. With around $5 for shipping, that’s the lowest total price we could find for this item anywhere. This case adds a flip-out keyboard to your iPhone, so you can text physically rather than virtually.