PulseAudio 8.0 brings automatic routing changes, OS X and NetBSD support improvements, systemd journal logging for clients, new LFE balance programming interface, moore flexible configuration file handling, and various other bug fixes and improvements.
The automatic routing work should be very helpful and long overdue. "In case a sound card contains more than one profile (e g analog and HDMI profiles), module-switch-on-port-available will now switch away from the profile when no ports are available. E g, on a HTPC with headphones and HDMI outputs only, unplugging headphones will reroute the sound to HDMI, which did not work before. In addition, we also remember the last used profile for a port, so the expected HDMI profile is chosen (instead of just falling back to stereo)."
More details on the PulseAudio 8.0 changes can be found via the FreeDesktop.org Wiki.