Have you ever used digital zoom before? It zooms in on the picture and adds information that is not there into the photograph.
Digital zoom is like you cropping a picture, enlarging the new image back to the original size, and then attempting to use information in the surrounding areas to enhance the stretched image created by enlarging the image.
I have never seen a digital zoom that looks as good as an photo taken without digital zoom, let alone "making it better, even if only by a little bit."
I can't name a single phone camera that has zoom, at least, without the phone being designed around the camera, rather than camera being a tiny little extra, I don't think the camera package is simply big enough to be able to fit an actual zoom onto in most phones.
buy a camera! For the size of the lens and Camera the iphone 3gs do fine for basic photo's. I am sure the 4G will be better. At the end of the day I use a Camera for really good pics. Then hope that my Cell phone works well as a cell phone. btw my camera totally sucks as a cell phone. I will contact Canon about adding cellular calling in there next camera.
First thing I do when I get a camera is turn the digital zoom off. Unfortunately, on the camera I use for work, that only turns it off in auto mode. In manual mode, digital zoom still works. I usually don't zoom anywhere near that far though, so it's not a problem.
Think of it this way, the processor in the phone is interpolating the image to magnify it.
If you want to zoom it, it's best to zoom in using photo editing software on a computer that is more suited to handle it. The digital zooms in cameras or camera phones is always a bad idea.