Instead flashing new program to your arduino internal flash storage, you can now copy the application binary to the SD card and run on the arduino. With the help of Pyxis OS, you will turn your arduino to be a PDA like system. You can have advanced graphics APIs and also run applications from SD card. The biggest problem is that you only allow to write the application in the Pyxis OS specific programming language:( But it is still cool.
In their website, they provide a free PFAT implementation for turning the EEPROM to a file system in AVR. it is free:)