Yes.
It's points not pixels (as I mentioned above).
However, for phones and performance we actually go as far as @2x and not 3x for images. This is usually what most games with lots of moving graphics do. (it reduces memory usage).
on importing, hyperPad assumes you're importing retina version (unless you turn the toggle off on the import popup) and will automatically create a halfsize nonretina version for you.
Edit: Actually pretty sure you can use @3x when exporting and manually adding the images to your xcode project. @Hamed will need to confirm though.