The update to the VA-API v1.0.15 library itself has API fixes, auto-generated Debian packaging support, refinements to the VA helper utilities, and has various fixes.
The update to the Intel VA-API driver (vaapi-driver-intel) brings fixes for VC-1 and MPEG-2 decoding. There's also memory leak fixes.
The releases were tagged by Gwenole Beauchesne, who left Splitted Desktop Systems to go work at Intel. The latest VA-API components can be fetched from FreeDesktop.org. The PowerVR, VDPAU, and XvBA drivers for the Video Acceleration API haven't been updated to version 1.0.15 (or been touched at all in many weeks).