I've also been investigating this topic. My findings so far are that the only two worth investigating are GotoWebinar and Adobe Connect. I am currently leaning toward the latter.
I should also note that Amy Hoy (ahoyhere from HN) and Thomas Fuchs use Adobe Connect to run their JavaScript and HTML 5 classes online which they've had a ton of success with. I've also been to some GotoWebinar webinars and they've been OK but the interactivity sucks. It seems Adobe Connect is good for more intimate, detailed affairs, whereas GotoWebinar is good if you need many hundreds of people just watching and sending moderated questions.
I should also note that Amy Hoy (ahoyhere from HN) and Thomas Fuchs use Adobe Connect to run their JavaScript and HTML 5 classes online which they've had a ton of success with. I've also been to some GotoWebinar webinars and they've been OK but the interactivity sucks. It seems Adobe Connect is good for more intimate, detailed affairs, whereas GotoWebinar is good if you need many hundreds of people just watching and sending moderated questions.