Crafting has been given a little shake-up in Cataclysm. Nothing as serious as the talent tree changes or the sundering of Azeroth but still some added fun. Maybe.
The first obvious change is that some recipes can give multiple skill points. My crafting addon of choice (Gnomeworks) shows this as a percent chance to gain a skillup. So some items show as 300%. Nicely this also works for green recipes which can show percentages <100%.
This means there are two tricks to play with crafting now. Firstly, consider crafting two items at 85% chance of skill-up rather than the single item at 100% that takes twice as many mats. Secondly, consider crafting the item that gives 300% skill-up just before it goes yellow (and reduces to 100% or less). These recipes tend to be more expensive so you can be better off crafting from 100 to 104 with single skill-up cheaper recipes and then 104-107 with the 300% recipe.
Another change is that a lot of crafted items are now a generic base item with random extra stats. For example, craft the base item Nightstone Choker and you’ll get one of several potential versions. There’s also a chance of getting blue items, some of which can sell well on the AH.
The final change involves high level crafting. This varies between profession but by and large you’ll be wanting vendor bought items and recipes from Twilight Highlands. This will require reaching level 84 and doing the first few quests before you’re in phase with these merchants. Some items are simple gold bought BoE reagents on limited supply (thankfully with a much boosted refresh time now). Others are recipes (or in the case of engineering cogwheels to go in the new head piece) that are bought with other crafted items. In the case of enchanting this includes the new rod recipe, which is BoP so all enchanters will need to level to 84 to be able to craft top end enchants.