4.1 Changes

Well this is pretty behind but I've been busy, okay? (I also notice a lot of traffic from the search terms "4.1 priest" which means people seem to be hungry for this information).
If you are looking for a full synopsis of the changes I suggest the Wowhead patch notes, as that is where I get most of my information, however I am going to do a run down of some of the changes that you should know as a healing priest. This will by no means be an exhaustive list of all the changes, but will outline things I think are important.
General

• Inner Fire and Inner Will last until canceled. While this is not the largest change it is one that makes sense. How often have you been running around in a dungeon and not realize that it has fallen off (especially now that it's hidden in that little buff box). It never made sense to me for this spell to have a limited duration (or limited charges as pre cata!) a big Thumbs Up from me.
• Dispel Magic now dispels two magical effects at once for healing priests. Its about time we got this back, while it is more of a PVP ability (I think) it's nice to have this back, it has bugged me since they took this away that all the other healing classes have one button to click for dispels and we have 2 (3 if you count mass dispel), so this is a nice little handout to make us feel a little less forgotten.
• 100% pushback protection while Channelling our Hymns . Quite happy about this, although it was pretty rare to deal with this in PVE it was a pain when it DID happen.

Holy

•  Chakra States now last until canceled. Wow is this awesome, I love not worrying about falling out of my Chakra state because I haven't been paying enough attention to my timer. Combine this with the four piece set and it actually comes off a little overpowered, but hey, Priests ARE Blizzard's favorite class right?
• Holy Word: Sanctuary has had it's healing buffed, and has a much cooler spell effect (even if it IS harder to see where the edges of the actual effect are :S). This is now a spell I am actually quite happy to use, while in the past it almost wasn't worth the GCD to me.

Discipline

•  Atonement now triggers from Holy Fire. Not only does it trigger from the direct portion, but I have noticed that the DoT portion seems to work as well (smart HoT ftw?). Combine this spell (faster than smite, and deals more damage) with the proper glyph and this change is huge for those atonement fights (especially Halfus!)
• Power Word: Barrier. Oh yes, the spell that Blizzard likes, but is never sure they like the way it works. It started off as a set damage absorption (like an area wide Power Word: Shield), then was changed to a damage reduction, and now they've decided it was over powered (now don't get me started on the Shaman Raid Wide Pain Suppression...). But alas they have decreed that this spell should have it's cooldown buffed by 50%, so now it has a 3 minute cooldown, up from 2 minute. Disappointing. Relearn those CD Rotations Raid Leaders!
• Power Word: Shield has had it's duration halved. Not a huge deal for PVE to be completely honest. No one is bubble spamming anyways (except Phase 2 Heroic Chimaeron), so bubbles were popping way before that 30second duration they used to have anyways.
• Divine Aegis has had it's duration increased (12s to 15s). This is a very nice change, as many of those Prayer of Healing bubbles were being wasted, and now...well they'll likely still be wasted, but hopefully less!

That summarizes most of the Priest Changes. I really encourage any good raider to go take a look at all the changes to the other classes as well (especially your fellow healers, and the priest changes I may have skipped), the more you know about other classes and how they work, the more prepared you are to adapt to changes in the middle of a fight, or change your strategy between attempts.