A week and a half ago the ACPI/PM 3.15 pull request was sent in by Rafael Wysocki when it looked like Linux 3.14 would be released and this Intel developer had to go off to the Linux Foundation Collaboration Summit. Rather than releasing Linux 3.14, Linus Torvalds ended up releasing 3.14-rc8 that week, and thus the ACPI/PM updates became stale. With Linux 3.14 finally now out there, Wysocki has re-sent in his ACPI/PM subsystem updates for the Linux 3.15 merge window. Besides including the original work, there's also a few more fixes that matured over the extra week within linux-next and are now ready for mainline integration.
Besides the faster suspend/resume support due to the kernel code using more asynchronous callbacks, there's a lot of other ACPI/PM improvements. Other noteworthy changes include device PM QoS support, updates to ACPICA, Windows 2013 has been added to the list of features for ACPICA to workaround some faulty hardware, battery / AC fixes, new device IDs, Intel RAPL clean-ups, Intel P-State fixes, CPUfreq / CPUidle fixes, and other fan / thermal optimizations.
More details on the Linux 3.15 ACPI/PM updates can be found via the new pull request.