Thought of the day: TAM was originally in Star Alliance, then joined OneWorld with the LAN merger. Now, there's a reasonable chance that LATAM could join SkyTeam eventually, even if at first they merely align with Delta.
I believe this would make LATAM the first airline that's been part of all three major alliances. There are certainly plenty of moves (FM to *A>ST, CO ST>*A, US *A>OW), but changing alliance twice is entirely unprecedented...