It seems like these days 3D is the hot thing in tech. We have 3DTVs, rumors of 3D iDevices and of course Nintendo's upcoming handheld the 3DS, which will offer 3D without the glasses.
Right now, there is no way to truly view 3D effects on the iPhone, but this 3DBoard by Apocolipse turns your Springboard interface into an almost 3D experience by using the phone's sensors to detect tilt and move the icons around against the background.
It's not available yet, but should hit Cydia soon for $4.
Just another reason to jailbreak your iPhone. In case you are wondering about how to go about doing the whole jailbreaking thing, check out our guide, here (jailbreak iphone 4.2). Keep in mind, the current jailbreak for iOS 4.2 is tethered. We are still waiting the untethered jailbreak, but hoping it will be around soon.