You beat me to the punch...I've had an FF window setup with features toward this to post here and at OT since yesterday, but I got sidetracked last night playing CoD 3.

A couple of corrections and additions though...
They are in development toward just one rifle nt multiple and it is not an FN variant, no more so than it is a variant or copy of the RobArms XCR which was the predecessor and basis toward the 'SCAR' program. FN just happened to name it's offering toward that program after the name of the program.
The lower is a modified AR style that will support AR and a second lower design to support AK mags and allow it to be multi-chamberable, and will be produced in a plastic material. Because of this it's likely the upper will be serialized instead of the lower.
The upper is a piston design featuring a tooless quick change barrel system produced entirely from a metal alloy. It's also completely ambi by design which means alot for those of us lefties and others who prefer to shoot oppositely, such as myself.
An emphasis with this offering is to increase durability while reducing weight and it's said to be lighter in feel than the FN SCAR-L (Light).
Additionally multiple sources including Magpul report the offering will run $1.4K. Now it's not known, yet, if that is a street price, list price, or govt. price...but no matter what price it is to be in that neighborhood undercuts the now known list price of the SCAR by approximately 40% (!).
In Belgium they call that a deal!
Below are additional pics as well as a link to an official PDF from Magpul toward it's layout and internals...
Link to the above fullsize PDF from Magpul -
http://www.magpul.com/Masada_inside.pdf
I'm totally psyched about this news.
Between this and the Robarms 'XCR' and the MGI 'Hydra', as well as the FN 'SCAR' these are the things that myself as a potential rifle buyer is looking for.
Lightweight, multichambering capability, durability, ambidextrous capability, ergonomics, and best of all it shouldn't cost a damn arm and leg to have.
The FN 'SCAR' and MGI 'Hydra' have crazy price tags attached to them. The RobArms 'XCR' has alot of good buzz behind it from owners but it's owner himself does not and they are a tiny company at that. As well extra bolts, carriers, and it's custom AK mags as a package runs $400 which is less spendy than same from MGI or FN, but geez man why does it have to cost so damn much. If Magpul can pulloff similar cost savings/reduction toward multichambering capability cost as they have the whole rifle then one would be looking at possibly $200 which is much less distatseful. Even if it were $400 for them too that would not be bad considering the whole cost of the weapon system as a total investment.
Additionally Kel-Tec has a very intersting package on the way as well.
More toward that in it's own thread though but I've got to go and play with my duaghter for now as she's pissed I sat here and wrote this up...
- Janq