Talk about synchronicity! Right after I posted the previous entry about Brainshark, I saw this press blurb from Hearst Electronics Group. They say that they conducted a survey of web seminar attendees and found that most prefer to invest 10 to 15 minutes per event, rather than an hour, to learn about new electronics products.
The VP-publishing director at Hearst Business Media said "They don't care if it's live or taped as long as they get their questions answered."
I think that's a little simplistic, but the fact is that for many types of specific information dissemination purposes, he's quite right. Look for ways to simplify your message, drive home the key information your audience really wants, and leave them hungry for more. Establishing an ongoing information sharing relationship is a very effective way to build trust and goodwill. (By the way, what do you think a business blog does?)
There is nothing magical about the one-hour webinar. If you can deliver your subject in less time, do it. Your audience will appreciate the break.