IHE has a story, though this strikes me as an easy case: it's outrageous, and anyone who live-tweets a conference should be immediately disinvited from the event, and any future ones.
UPDATE: So I guess even at 6:30 in the morning I should have realized someone would ask why this is my view, so let me explain briefly. The medium of twitter is not suited to discursive reasoning or extended analysis or argument. But philosophy presentations contain discursive reasoning and extended analysis and argument. Therefore a twitter version of a talk will necessarily mutilate it. Since mutilation of someone's work has no value, people who attend a conference should have the courtesy not to try to tweet the talks. If they do not have that courtesy, they should be thrown out. There may be fields where presentations lend themselves to tweeting; on that issue, I'm agnostic. But philosophy isn't one of them.
ANOTHER: Turns out if you diss tweeting, the twitter-sphere goes crazy! (Thanks to Peter A. for the pointer.)