We just played with both the new Apple keyboards, both wired and wireless, and found them actually quite good. It's no longer mushy, like the old keyboards, but almost exactly like the keyboard on the MacBooks now. They have the same space between the keys, and pretty much the same tactile feel when you press down on them. Which is great if you like laptop keyboard keys (like us).
The large wired keyboard has a num pad and pretty much looks like the old Apple keyboards. The Function keys are replaced with those new special keys like we saw on the net already, and work pretty great.
The small wireless keyboard, on the other hand is almost exactly like the MacBook keyboard. There's no number pad and the arrow keys are shrunken like they are on the MacBook (and other laptops). The keys themselves though feel exactly the same on both models. Which is to say, pretty good.
The keyboards are actually very thin and very low to the ground (desk). The back is raised, so it's slightly more ergonomic. All in all, it's quite comfortable, and I could type pretty fast on it (faster than Mercury News' Dean Takahashi, at least).