I read in an article on gamespot that Nintendo released
an accesory for the ds and gameboy advance on japan
called Nintendo Play-Yan
The Nintendo Play-Yan gives Nintendo DS users who feel left out from the Sony PSP's multimedia capabilities the answer to their problems.
Nintendo Play-Yan is an add-on peripheral that allows the Nintendo DS and Game Boy Advance portable systems to play ASF movies and MP3 files from an SD flash memory card. The Play-Yan has an SD slot for the memory card, and the entire unit slides into the GBA cartridge slot.
here's the link http://hardware.gamespot.com/Story-ST-15366-2094-x-x-x
so nintendo doesn't want to be left out with the multimedia offers that the other companies put in their consoles