While details are scarce, we can imagine a lot of popular carts (like the R4), if not all carts, will be affected. Should Nintendo and friends win the suit, selling and importing such carts will be illegal, meaning that people would have to resort to the black market to get their hands on one.
We understand why Nintendo and other companies would want to fight the good fight against piracy, but we can't help but fret over the impact on our precious homebrew hobby. At any rate, we'll give you more information as this case unfolds.
[Via Joystiq; Thanks, Kimiko!]