Of all the World of Warcraft professions, I would say that inscription changed in character the most from Wrath of the Lich King to Cataclysm. In WotLK, inscription was mostly about glyphs. Patch 4.0 killed the demand for glyphs, as you now keep your old glyphs when you respec. It also significantly increased the cost of production of glyphs, ending the previous situation where sometimes you could make a glyph for 1 gold and sell it for 60. In Cataclysm inscription didn't even get any new glyph recipes. You had the choice of skilling up either fast by making very expensive off-hand items, or slowly and cheap by making forged documents every day.
Nevertheless, once you reach 525 skill in inscription, the profession is still a money maker, at least this early in the expansion. The thing to make are Darkmoon cards, leading to level 85, iLevel 359 epic trinkets. Some of these cards sell for up to 4000 gold, while others are only worth a few hundreds. You know there is a tank shortage in the game if the tanking trinket costs only a fraction of the dps trinkets.
There are two reasons why Darkmoon cards are a money maker: There is a significant amount of "work" involved, and the prices for raw materials (herbs) are all over the place. I've seen prices for Cinderbloom, the most common Cataclysm herb anywhere between 2 and 8 gold. One factor here appears to be gold farmers: I recently bought 83 stacks of Cinderbloom from the same seller on the AH at just under 3 gold each. It is hard to imagine how a regular player would gather 83 stacks of herbs and then sell them at low prices to turn them into money quickly. Those 83 stacks of Cinderbloom netted me 88 inferno ink, so my cost were under 60 gold per ink. I could have sold the inks for easily twice that, but I decided to turn them into Darkmoon cards. I got reasonably lucky with the distribution, not getting too many of the low value Stones cards, and was able to turn my initial investment of under 5k gold into 15k gold. Not a bad profit for an hour of milling herbs and crafting.
Of course that sort of profit depends a bit on luck, on picking up herbs at low cost from the AH, and on being lucky with what cards you get. With time the value of those epic trinkets is going to fall, and then inscription will stop being highly profitable. I wonder what Blizzard thinks should be the sustainable business with inscription.