The truth is that the new Cataclysm zones aren't any different from our current zones in terms of spawn patterns. Fly around the edges of the zone, fly near "ridged" areas. The same logic that applies now is still valid. Deepholm is just a big round zone, so it's pretty easy to fly in a loop and spot plenty of ore. Uldum has a huge river in the middle, with desert all around. I haven't found any good reason to fly through the middle of it, but ore does spawn around the edges of Uldum. Twilight Highlands is quite mountainous, so there's ore pretty much all over. Vashj'ir is spotty when it comes to ore, if you're a Miner I wouldn't try to farm this zone. Mount Hyjal has a decent amount of ore, but apparently phasing really hurts the availability. If you want steady access to obsidium, don't quest in Hyjal.
As I mentioned in my previous post, you can level Mining in an hour if you stay focused and avoid the crowds. One of the best ways to avoid crowds is to start in Northrend. Rich Saronite has the same difficulty as Obsidium (425) and Titanium is higher than both of those. You should be able to achieve the same leveling results in Icecrown or Sholazar Basin that you would get in Mount Hyjal. The main reason to go this route is to avoid crowds. No one wants to be in Northrend after the Cataclysm launch and you may end up with the zone all to yourself. You'll get skill points a lot faster if you can mine all the nodes in a zone without interference from other players.
Once you hit 475 (470 with a Gathering enchant on your gloves) just hearth back to Ironforge/Undercity and fly to Twilight Highlands. You can also use the CoT portal in Dalaran if you prefer to go to Uldum for Mining. Uldum may have less competition due to being more difficult to access, but it also has less ore spawns.
Here are the skill requirements for Cataclysm nodes:
|425||Obsidium Deposit||Vashj'ir, Mount Hyjal, Deepholm|
|475||Elementium Vein||Deepholm, Uldum, Twilight Highlands|
|500||Rich Elementium Vein||Deepholm, Uldum, Twilight Highlands|
|525||Pyrite Deposit||Uldum, Twilight Highlands|
I've seen "rich" obsidium nodes in the Beta, but they went missing in the last month. This could have just been my bad luck, but if they show up anywhere it will likely be Deepholm. That's where I had previously spotted them before they disappeared. In any case, I wouldn't go to Deepholm until your Mining is 475. The vast majority of the ore there is Elementium and you need 475 to collect that. Bear in mind that you cannot get to Deepholm until you are level 82. Deepholm is only accessible by portal, which has a level restriction of 82. If you plan to power-level your mining on the first day, you have to skip Deepholm completely.
My recommendations for getting a Realm First in Mining would be to camp in Dalaran and set your Hearthstone to Ironforge or Undercity. Make sure you have a +5 Mining enchant so you can mine Elementium at the lower skill. You should also make a point to pick up all the flight paths between IF/UC and Twilight Highlands before release day. For Alliance the key flight point you need is Farstrider Lodge, I don't know what the Horde version is. On Launch day learn Illustrious Mining from the trainer in Dalaran and then fly to your favorite Saronite/Titanium zone. Farm both of those ores until you get to 470 (475 with no glove enchant) and then hearth to Ironforge/Undercity. Don't forget to stop by a flight master before you head out and pick up the Azeroth flying ability. From IF/UC take the griffon straight to Farstrider Lodge/Hordie FP, then mount up and fly to Twilight Highlands.
There is plenty of elementium in Twilight Highlands and you should have the zone to yourself. If you don't, I'm sorry :( Hopefully the other guy has a slower computer? At first you'll only be able to collect elementium nodes, but at 500 you'll unlock the rich elementium veins. There won't be a ton of pyrite, so from 500-525 you should be able to get the vast majority of the spawns. The western and northern borders have plenty of ore to keep you busy, last week on the Beta realm the respawn times were about 5 minutes for a full repop. That could be increased for Live, but I had no trouble farming just a section of the zone.
My daughter leveled Mining on her 80 Death Knight and got to 525 in less than an hour. If you're smart, the aggro in Twilight Highlands can be avoided. There are plenty of nodes out of range of mobs, just skip any that look tricky. If for some reason you don't get Realm First, you can still make gobs of money off the elementium and pyrite you'll be able to collect when no one else has any :)
Please keep in mind that my information could be inaccurate if Blizzard changes any of this before Cataclysm goes Live. They still have two weeks to continue tweaking before we see it. The skill levels of Northrend ore could be modified (unlikely) and the CoT portal in Dalaran could be removed (reasonable chance of this). Sometime between now and 12/7 I would do a dry run and make sure everything is working the way you want.
Good Luck to all of you and let us know how it turns out!