Seeing as it's been quiet for some times, I figured I'd put up a link to a somewhat important article. I myself have been rather uncertain as to what's gonna happen with the next patch, and how much of Cata's intended healing system will apply in end-wrath.
WoWInsider's Spiritual Guidance priest section has a nice column up about what will change soon, and what will wait 'till Cataclysm.
In a nutshell;
-Mana regeneration will stay the same
-Healing as it is now will more or less stay intact
-No need to use Heal, yet
-We'll get our new abilities and with that an opportunity to learn how to use them: Power Word: Barrier, Chakra and all its subspells and Smite+Attonement/Archangel will be in play
This keeps our cookie cutters fairly predictable - we still, for now, avoid all +mana talents and spec completely for throughput. Disc will simply get an additional cooldown as well as the Smite trick if they feel like playing around with that, and Holy will get its Chakra.
Long story short: do not worry about Heal yet, spec as you would in WOTLK, and stick to your original game plan - use additional tactics when you feel safe enough to get into them.
Edited, Oct 10th 2010 6:42pm by Mozared