We all knew it was coming, and now it's 100% official.
Nintendo's pre-E3 website has updated with the following remark about Mario Kart: Double Dash:
Pack eight players into your living room and turn up the fun when you connect two Nintendo GameCubes via the Broadband adaptor. It's intense action coming soon to 2 screens very near you!
We first told you that GameCube is capable of connecting via ethernet cable at last year's E3...where we actually saw the feature demonstrated. Nintendo is expected to unveil a comprehensive GameCube networking plan at this year's E3, including games that will support the feature and possibly hardware that will make LAN gaming easier to set up.
Thanks to the guys at Console.Be for the tip!