Think of them as a basic drop in handguard that looks different. They also have the slots cut in for drop in rail sections.
On a side note, the drop in 1913 rails that are currently available will work, but I think that Magpul should take a serious look at creating their own polymer 1913 panels. While aluminum rail sections are nice, I don't think that they are needed for holding a flashlight on many weapons.
OK here's another question, as per the magpul 2008 catalog, it states the MOE hand guard will have rail adapters at 2 and 10 o'clock. So is this saying there will be no way to mount a rail at 6 o'clock and therefor mount a VFG? I suppose one could drill their own mounting holes (the hand guards are only supposed to MSRP at $30 or so) and not feel too bad, but still I would think it would be a given to include them into the design.
Oh ok, it doesn't seem to mention rail adapters at 6 and 12 in the catalog, but I'd buy it coming straight from the horses mouth. Cool, mark me down for one when they're available!
Its funny the MOE stuff is supposed to be the less expensive Magpul line but I really like some of the items. This MOE handguard if they made it FF would be really nifty.