There's not a whole lot so say here that isn't already in the title but it only took about 4 hours for the R4i team to hack the 3DS after launch. You can't play pirated 3DS games on the device yet but you can play Gameboy Color and original DS games so things are starting off pretty well but you can expect Nintendo to push out a firmware update that will set R4i back temporarily. They did offer up an explanation about their accomplishment on their YouTube channel,
Let me just clear things up. This is not a 3DS flashcart. It is the R4 used on DSi. It is not possible to play 3DS games from it. You can't use your current DS flashcart (no matter what brand) on it. The R4 team has managed to hack the 3DS in order to make it run. Nintendo has made a "whitelist", built into the 3DS. It's a list that contains the names of all games that can be played on the 3DS, and guess what; the R4 is not on that list. These guys have modified this list, making it possible to run their flashcart. Therefore, YOU can not do this, unless you hack the system yourself. Expect Nintendo to release a firmware update to block the R4 cards once again.
Check out a video of the hack in action by hitting the break.
At least for Nintendo's sake R4i hasn't circulated information on how to jailbreak your 3DS yet like a certain someone did to Sony with the PS3 but I'd say it's just a matter of time.