Tigole has been joking around on the forums with a vengeance today (did you know that Northrend was originally going to be called "Blizzneyland"?), but he did provide us with a quick preview of all the patch changes for the next beta build coming up. Heroics, he says, have been retuned, and Blizzard is especially looking for feedback on endgame raid instances like Icecrown. Dalaran has gotten a little more "polish" (that's the shiny kind, not that there are more people there from Poland), and there will hopefully be a glyph vendor in soon to let players try out new glyphs of all kinds. Finally, he says performance updates have started, and that's a good sign that Blizzard is working on getting towards the final stages of the expansion development -- sounds like most of the early zones and items are as done as they're going to get.
He also, of course, says that there are class changes in the patch, with one of the most insightful notes we've seen yet: "You won't like the ones made to your own class but you'll think the changes made to the 9 other classes are all overpowered." It's true. If only all of the other patch notes could be so incredibly clear to players.