You guys think that there is any use of taking spirit trap 5/5 at lvl 70 ? or that depends on pve / pvp etc ?

if you're 70, the only reason i could see (note: personal opinion, very, very far from an authoritative blue position) is for serious pvp'ers. if you're grouped, and not the only dps'er (and how many times does that happen?), spirit tap will proc so infrequently that i can't see the benefit. regardless of your build i think it should be your first 5 talent points for anyone who does any soloing, but @ endgame, the benefits are so small compared to all your other choices, i just don't see it. i find it to be the most important talent for any priest, any spec, before 60 (unless you're paired @ the hip with a dps'er or neatshield).

I think those talent point are useless  for arena and pve ( raid) but if u farm its can be usefull but that depent how much spirit u have..... BTW am sorry for my basic english

That depends heavily on both your playstyle and talent spec.

For example, do you have any talents that add +spell damage from spirit, or do you know any priests with the improved spirit buff? The temporary bonus that increases your spirit also indirectly doubles the +spell damage that you get from spirit based on these talents. AFAIK, you can get a max of +35% spell damage and healing from your spirit, so assuming you have 350 spirit at 70 (big number, but whatever) you gain a standard 122.5 spelldamage constantly and 245 while spirit tap is active. It kind of reminds me of the warrior skill 'victory rush.'

That aside, I find it handy when I fight multiple things at a time... even in pvp. If you concentrate on one and kill it, no matter how hard it may be, the spirit tap might give you a significant edge towards killing the other things.

the counter question you wanna ask is, how good is blackout at 70?

Something I forgot to add above:

If you enjoy PvP-ing and collecting pvp and arena rewards, you mind as well steer completely clear of spirit tap and invest in a high-quality wand for the times you need to solo. Some of the 60s gear had spirit on it, but I don't know of much (if any) 70 priest pvp gear that has spirit.

So, the bonus spellpower damage I described above will still work... except itll be around 1/4 that in pvp gear.

I'm a little confused - I thought 5/5 in Spirit Tap means that every time you kill something you get a period of time where you have double your spirit - so for holy priests healing this would mean two things, faster mana regeneration (over the course of a fight may mean one extra heal which could be the difference between wiping and surviving) but would also mean that thanks to 5/5 inSpiritual Guidance you will get 25% of your spirit back as extra healing and spell dmg...  Does this not make it a must have especially for a healer?  What i'm not sure of is if this will proc everytime something dies in a group situation or if you would only get it activated everytime it's your mob to loot or something???

the ONLY time spirit tap procs is when you, the priest, take the mob's/opposing faction player's LAST hit point yourself. if you're healing in a group and SW: Pain (or another spell/effect) doesn't take the final hit point, spirit tap DOES NOT proc. you can take all of a mob's hit points but one, and as long as that one is not the last one, spirit tap won't do a darn thing for ya. so, if you're a healery priest and you almost exclusively group (pvp or pve), spirit tap is basically worthless. at least with black out, every time you land a shadow spell you get that chance of the stun.

Spirit tap can still be used for Healers classes it just takes a little luck and a lot of practice, for five man groups its not difficult to wait for a mob to get low on health and then mindblast SW:D for a cheap spirit tap. It becomes really easy if you have a group that understands the value of letting a priest get the killing blow.

Though for most endgame heroics and anykind of 10+ its a waste of points for you. In most heroics your attention (as well as Global Cooldown) will be elsewhere and wasting mana or sometimes burning yourself with SW:D can be a costly mistake.

So Spirit Trap will work in group only if Priest kills the mob??? I am a little confused because Spirit Trap does not work when I am in group healing, Can someone let me know please

IMO, Spirit Tap is decent for leveling, but not particularly useful beyond that.  I would also avoid it if you are intending to level as Holy or Discipline.  Instead, you should grab Wand Specialization for leveling instead.  After you through a DoT and a Smite or two at the mob, you can wand down the rest and regen at OO5SR rate for at least a few ticks.  Hell, I even kept Wand Specialization for a while after reaching 70 when I was still working on finishing up quests and we were only doing stuff like Karazhan, Gruul, and Mags and Unbreakable Will wasn't particularly more useful.