I have the Otterbox Defender on my iPhone 4 and it appears an excellent piece of kit. I've had it for approx 6 months and haven't felt the need to take the phone out yet. It's survived the general rough & tumble of being shoved into bags, saddlebags & trouser pockets with aplomb. The screen is totally usable through the hard front. It's yet to take a serious soaking and I don't intend to put it to an immersion test, anything with holes for plugs can't be expected to be waterproof.
Downsides, it adds bulk & weight to the phone, the rubber can drag when taking the phone out of pockets, and sometimes seems to attract dust & fluff. No one can see you have an iPhone, so you don't look cool......
Amazon appear to have the iPhone4 model for immediate delivery.
hereIf that isn't what you want I have an unboxed
Pixelskin HD, yours FOC if you want it.