Some people are slightly confused about what Gnome 3 actually is. The biggest myth is
Gnome Shell == Gnome 3
Actually its very far from the truth, in fact there is a lot of work that has nothing to do with user interface.
The second biggest myth is
Gnome will drop all support for Gnome-Panel
Actually it will be fairly easy to go back to Panel if you dont like Gnome-Shell its just “gnome-panel –replace” in command line.
Here is a list of some of whats going on (If I forget some please feel free to comment and add them).
You can see the release announcement here. For one its a redefining of the user experience with Gnome-Shell. Its also Gnome activity journal which will bring a new level of convenience to the desktop. There will be a lot of integrating of web technologies like webkit and javascript(which is what gnome shell is written in). A lot of outdated technologies will be deprecated and new technologies introduced. A new Gnome website too.
Gnome-Shell
There is some cool mockups and info about shell here.
This is the one huge change, removing the old gnome panel written back eight years ago and replacing it with a new fresh user interface. It is written in Javascript and uses CSS for theming. Gnome Shell uses Clutter for the display and it is very exciting looking at the beauty of Moblin which uses Clutter already. It features a simple desktop and an activities area that gives and overview of workspaces and allows the user to do all of what it does currently. It also has a built in notifications system and will soon get its own applcation indicators. Its not a huge change but it adds some new eye candy to the Gnome experience.



Gnome Activity Journal and Zeitgeist
This is very cool and has a load of awesome applications throughout the desktop. Zeitgeist is an engine which simply gets your activity from the programs you use, files you open, pages you open, code you view or edit and so on. Gnome Activity Journal uses Zeitgeist, tracker and telepathy to offer a complete timeline of your activities and the history of your files. Telepathy integration is also coming for to the journal for added collaboration.
What Zeitgeist offers is that it replaces GTK recently used and it can show you what activities you do most for each program. Zeitgeist and tracker will have all the information about you and your files and will add a never before seen level of information and relevance. Here is a nice video of Gnome Activity Journal in action.
Use of web technologies
The use of web technologies is very important, it enables developers from the single largest area of development to contribute. It also leverages all the goodness being done in this area. So we can use webkit to make a really cool program made using HTML, CSS, XHTML, Javascript, Ajax… Also as I mentioned above Gnome Shell is being written in Javascript to lower the barrier for new developers coming from other platforms.
Deprecation of old technologies and increasing use of new ones
Cleaning up is awesome, the Gnome platform hasnt had a big clean up in a long time and its starting to get crowded. The main changes are moving fully over to the dbus and moving to dconf. This will streamline the platform substantially.
The new Gnome Website
This looks really awesome.

So whats coming is a clean up, a new user experience, new technology and a new website. I hope this post clarifies Gnome 3 for people and I hope you are as excited as I am