A long time coming for sure, the free and open source racer SuperTuxKart has a big 1.0 release with LAN and online play enabled.
The game has a few different modes available including a normal race, time trial, soccer mode, battle mode and the newer Capture-The-Flag mode all of which can be played online.
They're not done yet though of course, they said it themselves that isn't not perfect and there are "improvements to be done, features to be added, and gameplay to be improved" but it's a massive step forward.
Personally, I'm impressed it has come as far as it has recently and it's probably the best free Mario Kart clone to be found. It's actually pretty fun too, a good game to chill out with. Now this huge addition with networking is out of the way, it will be very interesting to see what they move onto doing next.