All of the resources I've found (Yarr! and
http://urlshort.com/wotlk/site/talentlist.php) say that elemental focus lowers the cost of healing spells. And I would guess that Ancestral Awakening can proc onto your main heal target, if there's still healing to be done. Which basically means it can intelligently redirect overheals from crit. The spell might get its logic re-written to always select your main target unless its at full health, then the lowest-health target otherwise, which I think would be better for main-tank healing in general.