Athinira over on wow-europe forums has stated concisely what I think might be the best gem combinations for resto raiding:
"My suggestions if you want to boost your +healing:
Red Sockets - Teardrop Living Ruby (18 +healing)
Blue Sockets - Royal Nightseye (9 +healing 2 mp5)
Yellow Sockets - Luminous Noble Topaz (9 +healing 4 int)"
Now, after MT healing and raid healing in Kara, I have come the conclusion that I am more suited to being the duration healer (I am usually the last standing if a boss fight goes a bit awry... i.e. we screw up a bit) out of our group - Pally MT healer, Priest OT healer + target healer (e.g. sacrificed or charged target), Druid (me raid healer). Hence I get out of the 5SR more often than some druids and rely on spirit quite a bit. However, I am also of the opinion that if the MT/OT is taking spiky damage on some encounter, that I need more mp5 and +healing. SO... I think that overwhelmingly tempting socket bonuses aside, stacking Royal Nightseyes is the way to go for me, relying on nicely weighted spirit on my gear stats to do its job (I don't think I'm lacking in spirit and can even afford to lose my Bangle in shorter boss fights).
I'll have to give more thought to PvP gemming and also Heroics (although I doubt I will ever gem specifically for heroics as my +healing should increase enough with the same raid gems to raise my HT to a nice amount (max crit 8700 so far).