Another important GNOME 3 component was updated to version 3.10 for Ubuntu 14.04 Trusty Tahr: Nautilus, the default GNOME file manager.
Because Nautilus is also the default Unity file manager, it was patched not to use the new header bars under Unity, so if you use Unity (or other non-GNOME desktop environments), you won't notice any differences:
If you're a GNOME Shell user however, Nautilus (Files) should now use the new GNOME header bars, also known as client-side decorations:
Ubuntu 14.04 users: Nautilus 3.10 was promoted from the Proposed repository to Main a few minutes ago so it may take a while until you receive the update.
The only important GNOME components that still need to be updated to version 3.10 in Ubuntu 14.04 are GNOME Control Center (Trusty uses version 3.6.3 at the time I'm writing this article) and GNOME Settings Daemon (currently at version 184.108.40.206 in Trusty).