100% Fake.
1. If it were real, it would be running on a real DSi.
2. It's impossible to be real BECAUSE it's running on an emulator, DSi can't be emulated yet.
3. Nobody knows how to read files from the SD card, if they did, it would be all over every DS news site on the net.
4. At best it's a nice looking homebrew for the DS.
[edit] And those screenshots in the dsi hbc thread are of DSision2.