This is yet another application among the bouquet of utilities provided within Google Apps. It lets you create sites for internal purposes as well as worldwide publication. For instance, a group within the organization may want to put up a site in relation to the project on which they are collectively working. Such a site may contain information contributed by the group in collaboration. The target completion dates, processes, current status, etc. It may be updated anytime by anyone in the group. There could be number of such sites. Then, you may also want to put up a site for sharing information globally.
The Key features of Sites are :-
There are some sample templates which one could use. It is inevitable, with the continuous innovation taking place, new features are bound to crop up sooner than later.
This website is an example of a public site created with Google Apps. There are several others which were created for internal purposes. Those sites are shared with select people in the organization. Similarly you can deploy your own web presence for the world to see and also have sites for sharing within your own business.