I've hacked my statusbars to work with 3.0 somewhat (CPs/Targethealth). It's still my favourite statusbars addon because heath and mana are separate from each other and it has the best fading options.
to fix the combo display change in statusbars.lua
this:RegisterEvent('PLAYER_COMBO_POINTS');
to
this:RegisterEvent('UNIT_COMBO_POINTS');
and
return GetComboPoints('player');
to
return GetComboPoints('player', 'target');
Since I can't programm lua, just steal and pillage from other addons or update syntax changes like the combopoint one I'm still trying to figure out how to incorporate the new energy changes. I know how other addons do it, I just can't figure out to code it in statusbars style. How to change the player and pet energybar to update on OnUpdate() instead of OnEvent() when the new variable (predictedPower) which activates the new mode is set to 1.
I played with this on the PTR and I think the new smooth updating bars are nice to look at but not having them isn't really a gamebreaker. It's more of a cosmetic change and you can disable/enable it globally with (/console predictedPower 0 or /console predictedPower 1). Nevertheless I'll keep trying to get is to work and then there's still the thing about Deathknight runes coming with WotLK.