^+1 regarding Quick Sync, it accelerates only the H.264 MPEG-2 & MPEG-4 encoding - the software/plug-in support is currently limited. If you are going to be using Adobe Premiere then there are specific GPUs that allow acceleration in addition to the plug-in for Quick Sync.
Quick Sync - http://www.intel.com/technology/quicksync/index.htm
Article - http://www.anandtech.com/show/4083/the-sandy-bridge-review-intel-core-i7-2600k-i5-2500k-core-i3-2100-tested/9
Adobe Premiere acceleration official & updated - http://www.adobe.com/products/premiere/tech-specs.html
/Hack acceleration - http://www.studio1productions.com/Articles/PremiereCS5.htm
IMO - Wait the 2~3 weeks for the Z68 MOBOs, the information 'today' is very limited so it's impossible to recommend a specific MOBO. However, I would look at the i7-2600K CPU if your App supports Hyper-Threading.
Q - What Application(s) is/are you using?