While Nintendo hasn't uttered a word on the subject yet, Japanese financial paper Nikkei reports (via Andriasang) that the 3DS will allow you to install your software to the handheld's internal memory.
For those who aren't familiar with how this works, basically, you select your installed games from the main menu and can then play without needing the original cartridges. Now when I say "your installed games," I mean the 3DS games you purchased and didn't download from the Internet. Right.
We don't know how much internal memory the device will have, but this is still incredible news regardless.
3DS Features Software Install [Andriasang]