Gnome 3.0 or Gnome shell has released few months ago, with a lot of new/exciting features and amazing experience. Gnome 3.0 claims to be the next generation desktop because of its innovative way the user interacts with the desktop. That’s why Gnome3 has been developed from scratched instead of just appending some features in existing versions (2.*).
So there is nothing wrong in thinking that – Gnome 3 is just a preview of the next generation (upcoming) desktop (that you will notice in most of the Linux based Distributions) ; Fedora and OpenSuse is already using it in its new versions, while Gnome 3 can also be installed on Ubuntu 11.04 but the experience isn’t enjoyable with Ubuntu (because the PPA used for installing Gnome 3 is very unstable and often crashes Unity ..and eventually your desktop would become unusable).
Best Gnome 3 Distro : Fedora 15
Fedora 15 (Code Named as Lovelock) was released a months ago with a lot of changes and surprises – Gnome 3 as the default desktop was the greatest one! Fedora is a free and open source Linux based operating system, and it’s the core of the most popular open source OS – Red Hat. Fedora strictly follow open source principles so it is considered as 100% free and open source Linux distro. A lot of good apps and large community supports are available. Fedora itself is a rock solid and stable operating system even though it has very high release frequency (similar to Ubuntu, but Ubuntu is very buggy and unstable as compared to Fedora). Fedora is often the most popular choice as a desktop OS among the enthusiastic GNU/Linux users (with some experience).
Other Distro You may Try is OpenSuse although OpenSuse is more suitable in Office Environment but If can’t wait to try Gnome 3.0 and fedora seems a hard choice for you (I mean, you are an absolute GNU/Linux user) then better go with OpenSuse (latest version 11.4 has a lot of remarkable features and Fun!).