For existing Buzzword users the only real change is the requirement to access the service using an Adobe account so you'll need to either use an exisiting Adobe account or create one. They'll even move any existing Buzzword documents over to the new account if you want as well. Adobe ConnectNow, if you've never heard of it before it used be called Adobe BRIO, is a Flash-based web-conferencing application that will allow you meet with others online, share ideas, screens and files and even collaborate on a shared whiteboard.
Another very useful addition is the Adobe AIR, runtime version of Acrobat.com, which provides an easy way of interacting with Acrobat.com to allow dragging and dropping files and folders from your local computer directly into your Acrobat.com account, and browsing, previewing, sharing or publishing files easily from your computer. The interface is exactly like the web browser version so there's no need to learn two applications and it can be minimized to a widget to save screen space.