Any live demo in a presentation is very, very high risk. Live web browsing is no exception
- You need to get an Internet connection to work in a strange environment. If finding power lead extension can be difficult, and setting up projectors is not obvious while the audience is settling down, going online is a challenge of a whole different magnitude
- The momentum is gone. If you have 20 minutes to make your pitch, you cannot afford to break the carefully build up momentum in your presentation. Turning away from the audience, "Wait a minute, where is that link, it was there yesterday" will make your audience opens up their PDAs to check email.
- Unpredictable content. A large banner ad for a gambling site. A breaking news story about stock markets tumbling. A sighting of Britney Spears. Distractions that will not help your story.
There are obviously situations where you need live web pages on a projector to work together as a group. In an informal setting, why not open up a regular browser? The only exception for a browser inside your PowerPoint might people that run training courses, either on Internet use, or on using internal corporate intranets.
P.S. Not sure what stirred the blogging activity yesterday, LiveWeb seems to have been around for some time.