The goal of this project is to create a LiveCD to demonstrate GNOME. The initial motivation was to be able to send a GNOME LiveCD to journalists and news agencies so that they can test and talk about GNOME without installing it, but others have expressed interest as well. The infrastructure for this will be flexible, so that it can be easily customized and re-targetted- for example, to distribute a version with a custom splashscreen for a specific conference, to change the language for distribution by non-en_US gnome groups, or to change the software set to market to different groups (artists, developers, etc.)
Currently, downloading and playing with GNOME is a high-investment activity. We do a release, and reviewers and new users just have to take it on faith that it is interesting, or worse, they have to build the whole thing. Even on distributions where up-to-date packages are available, it's still a big investment to figure out what distro you are on (if you're already on linux, which a lot of the people we want to reach out to aren't) and then download everything, make sure your deps are right, and get it all installed.
This difficulty in downloading puts GNOME at a serious disadvantage relative to, say, Open Office or Firefox, where reviewers and new users can download one rpm or tarballs, install, and say 'huh, I like this', 'here is what is good about this', etc. For them, simple download means word of mouth is easier, identity as a project for reviewers is easier, big splash ('million downloads in the first day!') so on, so forth.
The goal of the liveCD is to fix these problems, as much as is possible for a large and complex project like ours. We want to make playing with GNOME and the linux desktop easy and informative- i.e., someone should be able to download /one/ file, play with it for a while, learn about the desktop, and think 'I want to use GNOME, let me go install it for real', or 'GNOME is really (easy to use|powerful|whatever), I should tell people about it.'
There are lots of secondary reasons: