For those not familiar with Gnome 3, check out this older (but great) video created for the GNOME 3 launch:
If you hardware doesn't support it, the classic GNOME 3 session will load instead of Gnome Shell:
As always, Fedora is first to introduce some of the features that will later on be available in most other Linux distributions. Like GNOME3 or "systemd":
systemd is a system and service manager, replacement for SysVinit and Upstart. After a six months shift, during which it has been more granularly tested, Fedora 15 brings in, by default, a new system daemon whose code is designed from scratch, with the objective to take the maximum advantage offered by modern Linux kernels. With systemd, Fedora 15 boots-up faster, particularly on SSD;
systemd is a system and service manager, replacement for SysVinit and Upstart. After a six months shift, during which it has been more granularly tested, Fedora 15 brings in, by default, a new system daemon whose code is designed from scratch, with the objective to take the maximum advantage offered by modern Linux kernels. With systemd, Fedora 15 boots-up faster, particularly on SSD;
Default packages in Fedora 15 include: Firefox 4 (4.0.1), Nautilus 3.0.1.1, Empathy 3.0.1, Rhythmbox 2.90.1, Evolution 3.0.1, Shotwell 0.9.2, Deja Dup 18.1.1, Transmission 2.22, Totem 3.0.1, Linux Kernel 2.6.38.6, GCC 4.6, Python 3.2.
Fedora 15 also comes with BTRFS by default. BTRFS is a new "copy on write file system for Linux aimed at implementing advanced features while focusing on fault tolerance, repair and easy administration". I don't know about Fedora, but in Ubuntu there are still some issues with BTRFS - if you're using BTRFS in Fedora, let us know how it's working for you in the comments below!
Another interesting new feature is a default "dynamic firewall". This may not be interesting for regular users, but it should definitely make system admins happy as the dynamic firewall makes it possible to change settings without restarting the firewall.