While every class is getting new talents and spells in Wrath, there are three big, brand-new additions to the game: Death Knights, Northrend, and the new profession: Inscription. We've known for a little while that the general gist of Inscription would be to add effects to spells you already have, like a knockback to your fireball - basically enchantments for your skills.
Now that the beta has gone up, we have a few actual examples of inscriptions and what they might need, though so far we still aren't seeing any inscriptions that add to spell effects. Inscriptions evidently require various kinds of ink, which will be made from herbs by a skill called Milling, which destroys five herbs to create ink (very like jewelcrafting's Prospecting). Parchment will also be required to create scrolls, although the items it's made from are not yet implemented. And what could this Mysterious Tarot be? Maybe just a high-level parchment, given that it requires the same reagents, only more of them? There's another skill called Decipher that "allows the deciphering of tomes, books, and scrolls," though what that might mean I"m not entirely sure.
We do know that people who have inscription (scribes? inscribers? inscriptors?) will be able to create scrolls, such as the stat scrolls we all know and love to vendor, as well as something intriguing called Scroll of Recall. Hearthstone scroll, anyone? At least I really, really hope that's what it is. I miss SoR from my MUDding days.
Possibly the most mysterious part of what we can see so far of Inscription is Glyph Mastery: "Unlocks an additional Glyph." Um, what? I have two guesses: it might let you make longer inscriptions (if inscriptions are multi-Glyph strings, like Diablo II rune words), or it might let you put extra inscriptions on the spells of yourself and others (if each inscription is a Glyph). I suppose we'll just have to wait and see; here's hoping it doesn't take them that long to implement Inscription.
I know many of you will be curious what, exaclty, people are going to need for Inscription, so you can get started stockpiling it now and make a killing when the expansion hits (hat tip to clueless_noob). So far, all I can tell you is that Peacebloom, Silverleaf, and Earthroot appear to be used in the beginning inks; it's a fair guess that some higher-level herbs will get used later on as well. So I'd say hold on to those low-level herbs – I know I will be, instead of vendoring them like I usually do.