PowerPoint 2010 has this new feature called Broadcast a presentation. This basically 
allows you to do a simple LiveMeeting like broadcast of a PPT to multiple participants, free of cost (if using live or your internal broadcast server). Do note this is not as robust nor does it have most of the features you are used with a web meeting application. But this is great to use for those quick internal meetings, family presentations and maybe for some wide broadcast community webinars.
To use this option you first use the Broadcast Slide Show button on the Slide Show Tab of the ribbon. This starts off the process of setting up the PPT to be broadcast.
Next you get a dialog asking you to select the broadcast service to use. PowerPoint Live is part of the Live Suite and is free. All you need is a Passport ID and you are ready to go. But then this is also a public site and anyone can access your broadcast if they know the URL (more on this later).
You can also host a broadcast server, which from what I understand is going to be part of SharePoint 2010. This will allow you have your own private Intranet/Internet broadcast server and you can put in any kind of 
authentication that works for you on those. I also expect third parties to setup broadcast servers and most probably MS may also have a private broadcast server as part of the BPOS offering in the online services space.
If you choose the PowerPoint Live option, which is the only one you can use as of now (as SharePoint 2010 will be available for tech preview in late Sep/Oct timeframe), you will be asked for your passport login info and then your Slideshow will get published to PowerPoint Live. I had some problems with the publishing when behind a corporate proxy and so check to see if it works in your environment.
Once published you get a link that you share with the people who need to see the slide show. This is where this differs from LiveMeeting/Webex etc. This unique URL (the session id is the unique part) gets generated only after you publish and each time you publish, you get a different URL. So you cannot share this with a set of people before hand. You need to publish the PPT and then share the URL at that time. Also as soon as you start broadcasting, you cannot edit the presentation. This URL is also use once only.
Anyone who has the URL can look at the broadcast. You have no way of see who is actually looking at the broadcast and no way to actually protect the broadcast. But since the session id use is a GUID, it is very difficult to predict a URL and see an actual broadcast unless you have the URL.
The PPT appears in the browser without the need for any ActiveX or other Add-ins. It also works great in both IE and Firefox (Pictured above). According to what I heard it also works with Safari and a lot of the mobile browsers. So people should be able to see this on PCs, Macs and mobile devices.
So for a person to attend the broadcast all they need is an internet connection, a compliant browser and the URL. They don't need a Passport Id as there is no authentication or log in required for viewing a broadcast.
Once you click the End Broadcast button the session become invalid and the URL can no longer be used.
Also I found that some Animations and Transitions do not yet appear exactly the same on the web. For example, I had a bounce animation on a object and on the web it just did an appear. I assume they have not yet got all the animations and transitions in the web viewer yet.
Note: All Screenshots are from Office 2010 Technical Preview. This feature/screens may change before the final RTM
).
