This is fake, and Matt is a huge liar.
Firstly, in order to make a video game for the
DS, you would need to purchase, from Nintendo themselves, an developer kit (code named Nitro).
The fact that Matt claims that it was an actual project for retail which was cancelled doesn't make much sense for Nintendo.
Secondly, for people speculating about the box art, it was from a competition set by
GBXEMU.COM - Your No #1 Source for Gameboy NDS Emulation back when the
DS was first released in the US (they did another competition similar to that, on what the final
DS would look like when it was first announced, pictures from that contest were bought up when hints of the
DS Lite were given).
Also, there's other sites that question Matt's 'claims', and this site simply says that very clearly:
Halo DS? Where is it IGN? | Game Stooge
It's an elaborate hoax set by an overgrown fanboy. The rumour of Halo
DS has been started and ended over and over again by every gaming blog you can point a finger at since Metroid Prime Hunters: First Hunt (the free demo given with the
DS).
Edit: I'd like to also add that Matt doesn't speak for Microsoft, Bungie, or Nintendo. He is a news blog writer, and has been proven wrong in the past. IGN, Gamespy, Gamespot, etc. Are all networks for news, nothing more.