It’s unfortunate but true, the downloadable software for the DSi will be region locked. This was expected, since it’s the same way with Wiiware and VC, but it’s still unfortunate. Nintendo gives the reason that:

“DSi is region locked because DSi embeds net communication functionality within itself, and we are intending to provide net services specifically tailored for each region.”

I really just wish that the marketplace would be universal, so anyone anywhere could download any version of any game. Or even better, if you download a game, you get access to all versions. So you could have downloaded Super Mario RPG when it came out in Japan, and then downloaded the US version for free when it came out here.

That’s the world I one day want to live in.

source: Gamasutra