While Richards already beat me to this, here's some expanded info on the Eberron article:
The article's main point can be summed up in this sentence: “So, while you’ll find all the standard classes from the Player’s Handbook running around Eberron, each one will have a new look, feel, and flavor that fits nicely in the setting.” The article then goes through each class briefly and describes how it fits into Eberron. It also mentions that Psionics, while not required, are accounted for.
There will also be new base classes, of which they give the Artificer as an example: “These highly skilled characters have a knack for creating, repairing, altering, augmenting, and employing magic devices, items, and constructs.” They get all item creation feats, a free pool of “XP” to spend on items, spell-like abilities called “augmentations,” and more.
The “Master Inquisitive” prestige class is also presented, fitting into the issue’s spy theme. Its class features focus on discerning truth. One comment of note in the article is that prestige classes in Eberron will be more than just a name with a set of abilities, but also linked into the world via organizations.
Finally, four Eberron feats are given: Action Boost, Dragon Rage, Flensing Strike, and Haunting Melody.