Japanese sources claim Nintendo is planning to release a new DSi with a larger screen. The rumor is that the Japanese market will receive a 4-inch version of the DSi by the end of the year, for the same price as the current version which features a 3.25-inch screen.
The four-inch dual-screen screen version will have all the same features. Nikkei says it will launch in Japan by the end of the year. It will cost Y18,900 - around $200 - which is the same price as the standard version.
It apparently comes in response to requests from older users in Japan, and is presumably targeted at people desperately trying to fend off Alzheimer's by playing Brain Training. The standard model has a 3.25-inch screen. A four-inch version would put it on a par with the Playstation Portable.