I don't know if or when embedded passives will become the "next big thing" in PCB design, but they are on the way. We, at Screaming Circuits, have been asked about the use of embedded passives a few times.
The purported advantages of the technology lie primarily in the ares of cost reduction and space reduction. You could potentially get your bypass caps much closer to where they need to be as well. The space parameter is pretty obviously an advantage, but the jury is still out on costs. I suspect that at this moment, it's pretty difficult to find a board house that can fabricate a PCB with embedded passives.
If you're not familiar with the concept, capacitors or resistors are built up on the inner copper layers of the substrate. There are a couple different methods used such as plating, printing or thin-film. As shown in the illustration, the resistors and capacitors inside the PCB negate the need to mount them on the outside. I can see rework being a problem if any of those embedded parts has issues.
In terms of assembly, we wouldn't treat such a board any different than any other PCB. If your fab house notes that there are temperature or any other restrictions, let your assembly house know. Beyond that, all the standard rules apply.
Note from Forbin: Colossus is watching