Honestly I think it is obvious that if the new line of all macs has not been filed yet, it is for several reasons, that gathering all the information we know, could be summarized as:
1. The non-availability of new processors IB for some models of MBP and MBA.
2. The public presentation of Mountain Lion, but the new Macs do not think they will leave from the beginning with ML, I think Apple wants to make your presentation as it deserves in one of the new Macs at WWDC in order to show all possibilities and sell not one but two products that will make the impact greater.
3. The "redesign" of the whole line. I will focus on the range MBP, which are what interest me. We've been going with rumors of new laptops out every month of the year and still waiting. In my opinion, this are good news and should not to be treated in a simple HW update, because if so, with the new IB already on the market, at this point would have seen the launch of some products of the range a few weeks ago. Putting a little logic and gathering all the information we have, we can imagine that we do not expect a radical redesign, rather, I think that it will be a important and necessary redesign according to the continuity that is following Apple. This would be; keep the optical drive, increased battery, new processors, stylish design lines 'Air' softer and thinner body and weight, and last, the point that generate to me more doubts, Retina displays. It would make non-sense that with the imminent presentation of ML with support HDPi resolutions, the new MBP have 'standard' resolution and not take advantage of this OS functionality until many months or a year.
So in my opinion the shots can go through here, and the delay is due to this reasons, so do not despair in the meantime, but of course, is only my humble opinion. In a few months we will see who was less wrong.