Well, I've seen only the barest hint of rituals, from a playtest round a few months back -- nothing in the preview stuff at DDXP, so I can't tell you much about anything, really.
Luckily, like I said, I don't know much of anything to tell you. Here's my basic understanding of the way magic is shaking out, based on what's public from the DDXP stuff and some educated guesswork . . .
It looks to me like they've identified three categories of "magic" in the game. Attack magic, support magic, and more involved magic.
Attack magic has become most of the standard action at-will, encounter, and daily powers.
Support magic, by and large has become minor action powers (also at-will, encounter, and daily) or has been combined with attack powers (Buffs, for example, are not primarily side effects of some specific attacks that clerics and paladins make.)
Ritual magic, then, is where that "other" magic goes. Divination magic, for example, makes a great candidate for ritual magic. So does long-distance transportation magic, communication magic, some transmutations, etc. Probably some longer-lasting Buffs etc. That's all guesswork, but that seems to be the direction they're going.
Frankly, the idea of rituals is another one of the things that I really like about the game. It has always bothered me a little that with only a few exceptions all spells in the game can be cast in 6 seconds or less -- fantasy literature is full of examples of ritual magic, extended incantations, etc.
But, really, I've seen basically nothing of ritual magic so far, so this could be WAY off the mark.
-j