As a result, we're going to only look at the Enhancement tree.
Tier 1: Levels 10-14
Shield Specialization - 5 points. Even at level 70, the 5% mana increase is going to equal 300-400 mana, enough for 1 extra lightning cast. Compare that to 5% increase in block and 25% increase to how much you block? No brainer. Shield Spec rules, even at high levels.
Tier 2: Levels 15-19
Thundering Strikes - 5 points. You want to crit as often as possible.
Tier 3: Level 20
Two-handed axes and maces - 1 point. If you want to really do a lot of damage at the lower levels, take this. I keep it even at high-level, as there are some nice 2-handers out there for resto/enhancement too.
Tier 2 and 3: Levels 21-24
Improved Ghost Wolf - 2 points. This is your get-out-of-jail card. A fast transform can let you flee a fight with your life. I lose it at 60, but for leveling it's great.
Enhancing Totems - 2 points. 15% increase to your two primary buffing totems. This means higher damage, more crits, better dodging.
Tier 4: Levels 25-29
Flurry - 5 points. Faster attacks? YES PLEASE!
Tier 5: Levels 30-33
Spirit Weapons - 1 point. Yay for parry! The 15% threat reduction is great for grouping. And it's the pre-requisite for dual-wield!
Elemental Weapons - 3 points. 40% increase to Windfury. Windfury is your bread and butter. Once you get it, you put it on your weapon and never take it off. Some folks like Rockbiter. Let em - damage works out about the same in the end, but Windfury attacks still let you get procs on an important talent later on. [EDIT: Changed Windfury to Elemental. I must've had the buff on my mind]
Tier 3 - Level 34
Anticipation - 1 point. I hate that you're stuck with 1 loose point at level 34. 1% dodge is good, much better than 2% armor, so I place the point here
Tier 5 - Levels 35-39
Weapon Mastery - 5 points. 10% extra damage with all weapons. 'Nuff said.
Tier 6 - Level 40
Dual Wield - 1 point. Are 2 weapons really better than one? I played with both, and while I think the end damage is comparable, it's more fun to watch your shammy attack with 2 weapons.
So here's what your talent tree should look like at 40: http://www.wowhead.com/?talent=uZVVbdq0sVz
at 40, you can swap out to chain armor and have 2 weapons. It's also time to get a mount. You could respec at 40, removing imp ghost wolf and 2-handed weapons, as you now hopefully have a mount and definitely have dual-wield. I prefer to keep this all the way to 70 though, so we'll continue.
Go get your chain, still focusing on str/sta/agi/int, and get 2 weapons. For maximum Windfury damage, get the slowest, highest top-end damaging weapons you can find.
Let's move on to 40-60, shall we?
Tier 6 - Levels 41-44
Stormstrike - 1 point. Instant attacks, and then increases your post-attack shock by 20%. YAY! More damage!
Dual Weapon Specialization - 3 points. This helps a lot in hitting with your off-hand. More hits = more damage
Tier 7 - Levels 45-49
Unleashed Rage - 5 points. 10% AP increase for you and party members after a critical strike. It's not much to start, but you can never say no to more damage
Tier 8 - Level 50
Shamanistic Rage - 1 point. Mana regen from hitting things? Oh yes! Now, this relies on high attack power, so to maximize mana regen, drop your Strength of Earth totem before going into a rage. If you're in a party and have been battleshouted by the warrior, even better.
Elemental Tier 1 - Levels 51-60
What?! But Paul, you said this was an Enhancement Build!! Yeah, I know, but you want more damage, and you want it cheaper and faster, right? Elemental is a great side-arm to enhancement.
Convection - 5 points. More mana-efficient offensive spells.
Concussion - 5 points. More damaging offensive spells.
And now the push from 60 to 70. It's interesting, because the last 10 levels give you a couple of options. Help your healing and get cheaper totems, or fill out your enhancement tree:
Restoration Tier 1 - Levels 61-65
Tidal Focus - 5 points. Cheaper heals
Restoration Tier 2 - Levels 66-70
Totemic Focus - 5 points. Cheaper totems. You use totems a lot, so this is great.
So your build looks like this: http://www.wowhead.com/?talent=hEZVVbdq0sVuqoV0x
Enhancement Fill-out - Levels 61-70
Tier 6 - Mental Quickness - 3 points. Reduce the cost of your shocks even further!
Tier 2 - Improved Lightning Shield - 3 points. Do some damage back!
Tier 3 - Anticipation - 4 points. Max out that dodge
In this case, your build looks like this: http://www.wowhead.com/?talent=uEZVVfdE0sAuqo
So there you have it, 1-70 as an Enhancement shammy, with a couple of different possibilities towards the end. Let me know what you think.