While Nintendo has announced the DSi for Japan this November, the company is holding its release elsewhere. Nintendo of America president Reggie Fils-Aime has stated that the newest DS iteration won't be released in the U.S. until late 2009. (Good news for Europeans, the DSi is being slated for Spring 2009.) Bad news: Nintendo is region locking the DSi. According to the company:
DSi software (software that is only compatible with DSi) is region locked, eg: European DSi software can only be played on European DSi consoles... Nintendo DS software however is region free so you can play any DS software on DSi from any region. You can also browse the Internet on your DSi wherever you are in the world and exchange your photos with friends from around the world... 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. Also because we are including parental control functionality for Nintendo DSi and each region has its unique age limit made by different independent.
So to summarize, both DSi cartridge games and downloadable DSi games are region locked. Regular DS games still are not. Nintendo: "DSi software is region locked" [CVG]