This is the build
You may be thinking that I have left out some seemingly vital skills out (you may be right, I'm not saying this build is perfect), but here is a breakdown:
Corpse Spiders (rune: Leaping Spiders)
Wonderful alternative to poison dart. There has been a lot of talk about leaping spiders on the forums lately and to be honest, if you use it as intended (throwing the jars tactically round corners etc.) it pans out a lot better than others.
Spirit Barrage (rune: The Spirit is Willing)
Underused skill mainly due to how much mana it uses for against single targets. With the mana regen in this build, it is a very viable single target ability especially when used in combination with Haunt. The fantastic and unique thing about this ability is you can shoot enemies through almost anything (especially good against the Waller affix). Also, it's great for shooting guys hiding behind their invulnerable minions, as it just glides right over the top of everyone and POW, right in the kisser.
The Spirit is Willing is a great rune that refunds a bit under 50% under of the initial mana cost. When used in conjunction with other mana regens in this build, you can literally spam it (to an extent) on single target mobs to great effect.
Wall of Zombies (rune: Barricade)
In my opinion a must have ability, especially with the Barricade Rune. Invaluable ability when adventuring through narrow areas, totally blocking off enemies while you tirelessly lob spiders in their faces. It also does a considerable amount of damage and when used right can save you from a lot of dangers. Barricade is a must have as it widens the wall!
Spirit Walk (rune: Honored Guest)
Obvious choice and should be included in almost every build. It's our 'oh !@#$' button and when used in combination with the Honored Guest rune, gives a hefty mana regen whilst escaping at the same time. If you haven't been using this ability yet, do it.
Grasp of the Dead (rune: Unbreakable Grasp)
Another vital choice for WD's. The Unbreakable Grasp rune is also important, causing enemies to be slowed by 80%. This is our main kiting ability and should be used at all times. Again, if you're not using this then do it now. Also great as an AoE whilst lobbing spiders all up in their grill.
Haunt (rune: Draining Spirit)
A wonderful dot ability when combined with Draining Spirit. This should be used in combination with Spirit Barrage whenever possible as the mana regen from the rune (and Rush of Essence) means you rarely run out of mana, especially when you have haunts on multiple enemies. This doesn't mean you should be Haunting everyone though.
Gives you a second chance after 1 shot by Cydaea's tiny little spiders, oh and everything else. When used in combo with Spirit Walk, you can escape most hectic situations. Also reduces Spirit Walk cooldown by 2 seconds.
Rush of Essence
Refunds 30% of the mana cost from 3 of this build's abilities. Means you can pretty much spam Spirit Barrage on a Haunt-dotted boss.
Gives a nice boost to our base mana pool whilst giving a passive 1% mana regen.
I hope those explanations were enough to get the jist of how this build would work. I've tested it out in most areas of Inferno (minus Act 4) and works really well overall once you get used to it. Again, it's not a perfect build or 'the' build to choose post 1.0.3 but give it a try. Also, apologies if this has already been discussed somewhere previously on the forums, this is entirely my own experimentations.