What DPI should I have photos at for iPad?

Question

I understand the ideal resolution for photos on the iPad is 1024x768. What DPI should I save them at for the optimal display quality?

Answer 1

But it won't make a large file size smaller right?
If your files are managed by iPhoto or Aperture on a Mac, then yes it will. You need only compare the storage space allocated for your iPad photos against the storage space required for the original photos in the managing application. For example, I have 3 April Aperture albums currently installed on my iPad. On the iPad they require a bit more than 200 MBs of space. The original files that remain stored on my hard drive by Aperture take up 600 MBs of space. The amount of storage space saved will depend on the format and dimensions of the original files. I.e., the less compressed and larger the original file, the more space you will save during this automated optimization by iTunes as it syncs the content. Conversely, the smaller and more compressed the files you sync via iTunes, the less savings your will realize until you reach a point where no optimization takes place and the iPad file is the same as the original file. I don't think we can explain this in any simpler terms here.
As to the dpi vs. ppi (and/or lpi for that matter), I assume the poster was left-handedly attempting to point out that the terms have somewhat technical differences and should be applied more judiciously with respect to the medium or device to which you are making your reference. However, most of us did realize what you were trying/meant to say.