Divineo China posted this news:

M3 team, maker of the M3 Adapter, now release a new revolutionnary passkey system with the PassCard! Fully in stock today.

Heres some info:

Passscard is the perfect flash card boot-up solution for DS LITE & NDS .
It is compatible with most types of flash cards including M3, Neo, SC & G6 etc.

Plug & play! Simply insert both PASSCARD & flash card into the slots of NDS and that's it: Music, Movies, Freeware, Homebrew games and other files stored on your flash card can be launched.