One of the key things that we focused on for Windows Vista was improving the experience for mobile (laptop) users. If you are like me, you spend quite a bit of time running around with a laptop. However, when I am in my office, I tend to use my desktop. The primary way that I share files between my desktop and my laptop is by storing them on a Windows Server (it's also the primary way that I make sure that my files get backed up). For example, at Microsoft we redirect the "Documents" folder (previously known as "My Documents" in Windows XP) to a share on the server (of course, we use access controls on the folders to make sure that I am the only person who can see my files).
By redirecting key folders like the Documents folder to a file share, my documents are available to me no matter which one of my Windows PCs I am using. The problem of course is what happens when I don't have access to the server -- such as when I am not on the corporate network or perhaps sitting on an airplane. Frankly, the same problem exists with any file share that I might try to access when I am not on the corporate network.
Microsoft, Windows vista, Offline+Files