Metaforic's MetaFortress technology, to be used in games by Nintendo and six other publishers starting this year, uses code stored in the actual game that detects the patching used by flashcarts, and then disables the ROM. "We take any DS game and inject a security scheme into the game itself," Mclennan told Gamasutra. "It turns each game into its own security system. Every time we apply it to a different game, it's a different security system."
Though he admits that the software could be hackable eventually, it would require a separate effort for each individual game ROM. "We add so much security to it that it will take a very long time to hack." Mclennan claims that even flashcart firmware patches will be unable to neutralize MetaFortress, though he didn't specify why.
Though Mclennan thinks flashcarts should be illegal, he "sympathizes" with the homebrew community. It wasn't his goal, but disabling flashcart-based piracy at the software level obviates the need for anti-flashcart legislation, which could be good news for homebrew fans.