Later tonight, Justin Smith will open his home in Washington’s baronial Kalorama neighborhood for an “informal get together” to celebrate Semafor, the new global media start-up that he and Ben Smith plan to launch this fall. The event, which is “not a launch party,” according to the invitation, is nevertheless among the most buzzed-about shindigs on the White House Correspondents Dinner circuit this year—largely because, three and a half months after the Smiths announced their start up, and then semi-breathlessly kept announcing it in a series of early leaks, almost no one in media or politics has any idea what it’s going to look like, who’s going to be writing for it, or how it intends to differentiate itself and follow through on its promise of better serving the 200 million college-educated, English-reading people who, according to the Smiths, are underserved by the myriad English-language news organizations that already exist.