Update, 3:57 p.m. Per CNN's Brian Stelter, IAC fired Justine Sacco on Saturday. ""We take this issue very seriously, and we have parted ways with the employee in question," the company said in a statement. 

Original: Late Friday afternoon, before boarding her long flight to South Arica from London's Heathrow airport, InterActiveCorp communications director Justine Sacco tweeted a "joke." It went over poorly. That is probably the easiest way to sum up the ongoing Sacco saga, which now involves questions social media's role as judge, jury and executioner in the public square. 

Sacco tweeted this before her flight to South Africa for the holidays, presumably to visit her family: "Going to Africa. Hope I don't get AIDS. Just kidding. I'm white!" Her joke wasn't funny. But it was a prominent PR executive for a major corporation making a joke she should know better than to make, and in no time the world noticed. Sacco's tweet was then picked up by Valleywag; IAC owns plenty of web properties, like Vimeo, Ask.com, Match.com, The Daily Beast and Dictionary.com. Things started to heat up from there. 

Hat-tip to Business Insider for the capture:

IAC issued a statement against the tweet, and removed Sacco from their corporate website. Sacco's offensive tweet, and her entire Twitter and Facebook accounts were deleted shortly after she got off the plane. Aids for Africa registered JustineSacco.com and used it to distribute information about AIDS research and fundraising. (Donate today!) Apparently her dad is furious. But, so far as anyone knows, Sacco remains employed by IAC. 

Anger poured in at a steady rate over social media while Sacco was in the air, protected from the angry mob that started "taking unconscionable delight in the misfortune of others." Buzzfeed lists were made. Twitter ridiculed the comms director for her horribly racist tweet, and started theorizing about what will happen once she emerged from her airborne protection. #HasJustineLandedYet became the toast of Friday night Twitter. 

IAC eventually distanced themselves from Sacco, but had to explain they couldn't take immediate action because Sacco was unreachable — you can't call someone on an international flight: 

This is an outrageous, offensive comment that does not reflect the views and values of IAC. Unfortunately, the employee in question is unreachable on an international flight, but this is a very serious matter and we are taking appropriate action.

Her job status is currently unknown. 

But then something strange happened — someone actually went to the airport, watched Sacco get off the plane, took pictures of Sacco and listened to Sacco speak with the people who greeted her at the airport. Zac even spoke to her father. (Some information on social media said he was identified as Desmond Sacco, a South African mining billionaire, but this is apparently not true.)

Sacco's father said he's "incredibly ashamed," called his daughter a "fucking idiot," and condemned her comment: 

The Internet had figured out her flight information — Google offered the info when you searched her name Friday evening — and Zac, who is not a reporter, decided to meet Sacco at the airport. "I live close enough that the trip didn't matter," he told one Twitter user, when asked why he went to the airport. "I couldn't believe her tweet. Had to see of it was real." 

The reaction over social media, from which Sacco could not defend herself, prompted questions about the roles Twitter and Facebook play in these scenarios. "So is something like the Justine Sacco tweet-mob good because it reinforces mores about social behavior, or bad because it is mob justice?" asked GigaOm's Matthew Ingram on Saturday morning. Mashable's Chris Taylor wondered whether "the mob's response" fed and strengthened the beast that is Justine Sacco: 

There's a fine line between slamming Sacco for her blatant what-guys-I-was-just-kidding buffoonery, and taking an unconscionable delight in the misfortune of others while playing Big Brother on their lives. Quite apart from anything else, that sort of attention may play into the worst tendencies of someone who would write that. It grants her notoriety, maybe even a career in news channel punditry. She can pour out an apology to Barbara Walters.

What happens next is anyone's guess. IAC may stand by her, perhaps at least through the holiday season, or they may give her the boot in short order. The company has not issued a new statement since she landed. But, let's be real here, this is an Internet bred and born controversy — if she pours out an apology anywhere, it will be on Katie Couric's new Yahoo! show.