What does this mean for Fedora?
Short answer: Everything.
Longer answer: This is possibly the biggest single change we have done ever since Fedora Project was formed. It empowers the volunteer community at large to have more direct access to packages in Fedora including those in what was known as Fedora Core.
Before this merge, no one outside of Red Hat had direct commit access to packages in Fedora Core. This single repository along with a shared open and external build system changes the game drastically.
This is the first time (that I am aware of) a distribution that is sponsored by a major commercial Linux vendor has allowed everyone a equal footing in the repository resulting in a pretty big change for developers involved that would benefit end users in more suble ways. More on that follows.
Other distributions that I can think has different models similar to what we had in Fedora Core and Fedora Extras before. Mandriva has contrib (which Red Hat Linux had for a breif time too). Opensuse appears to use the web based build system. Canonical has universe and multiverse.
Fedora Extras is already available as a standard default repository for a long time now and it might not be immediately why a merge is beneficial.
1) Common infrastructure
2) Single repository
3) Wider community access to packages in the repository
4) No more limitations like Fedora Core packages not being able to depend on Fedora Extras packages which leads to benefits like enabling better functionality.
5) Single Live CD, DVD and regular variants. You can get a selected focused spin like Fedora KDE Live CD in a single disc or you can get the entire repository in two DVD's. If you want a different set of packages you can create your own spin optimized just for your own environment. The distribution composing tools like Pungi or live cd tools that we use to build Fedora 7 are already available in the repository.
You might already be aware that we have millions of Fedora users (nearly about 3 million just for Fedora Core 6) but do you know the stats for contributors?
Thanks to Mike Mcgrath I do have some information on that.
122 core packagers for 1178 source packages
302 extras packagers for 2968 source packages
Total: 424 packagers for 4146. 85 @redhat.com addresses
some packagers will be listed twice up, once with their @redhat.com address and once with a personal address.
Extras Development: 2968
Core Development: 1178
I am estimating the combined amount of binary packages will be around 8000.
Number of people that have signed the CLA: 1188
Number of people who are signed up as ambassadors: 205
Number of people working on documentation and translation: 104 (actual commit access)
Dozens of people working on artwork, news etc. All and all it's a very exciting day for Fedora.