quad tree based motion compensation (currently only 16x16 & 8x8 OBMC blocks, but can be extended to other block sizes easily)
different intra block coding (previous was just an ugly hack)
1.8% bitrate reduction -0.01PSNR (foreman@352x288 qscale=8)
1.5% bitrate reduction +0.05PSNR (foreman@352x288 qscale=1)

Originally committed as revision 3416 to svn://svn.ffmpeg.org/ffmpeg/trunk