http://kotaku.com/5503312/nintendos-...-digital-games

Nintendo's DSi XL hardware manual plainly states both that all DSiWare downloads "are for use only on a single Nintendo DSi." The manual also indicates that "software downloaded from Nintendo DSi Shop is licensed to you, not sold." What that adds up to is that, while Nintendo is selling people a new DSi to buy, it currently expects its consumers to pay for downloaded games all over again — or do without them.
Licensed to you, not sold.