The short of the DSi:

Smaller Size
Bigger Screen Size 17% Bigger
3 megapixel Camera
SD Memory Card Slot
No GBA Slot (Gameboy is Officially Dead)
DSi Shop with DSiWare
Price for DSiWare 200 to 800 Points
Consumers will get 1000 Free Points Good to March 2010
Pricing for System around 180 Dollars in white and black
Released Dates: Japan Nov 1, USA TBA