Hitting the mainline VA-API acceleration library (libva) this week was initial support for VP8 encoding. This VP8 encoding support now complements the MPEG-2 and H.264 encoding support of VA-API. A few months ago, VP8 decoding support was added to the Video Acceleration API. This will allow for VP8 video encoding to be done on the GPU of supported hardware/drivers rather than the CPU, assuming you're using a framework like GStreamer that is able to take advantage of VA-API. The timing of this code is for the upcoming Broadwell processors with their graphics cores having VP8 support, albeit no hardware support yet for VP9.
The VP8 encoding support hit libva with this commit but there hasn't yet been any VA-API Intel driver commits for supporting it by their graphics hardware. Broadwell is expected to be out in time for Christmas while a few weeks ago we discovered the Broadwell graphics marketing names.