This is not an April Fools' joke, which is why I waited until today to post, rather than posting on Friday when I found out about it.
Reliable inside sources have said (including GW sales reps to indie stores) that new metal models are not being produced. All that is currently available is old stock, and empty SKUs are being withdrawn from sale and are now OOP in many cases.
The story is that the recent massive increases in metal raw material prices have made it more financially sensible to switch as many models as can be justified by volume sales into injection molded plastic, and convert the remaining metal moulds for use in spin-molded "resin". GW have something like 15,000 active spin moulds (and 25,000 inactiiv ones) so it makes commercial sense to re-use them rather than scrap them and start from scratch with a completely new technology for these models.
Now there has been much speculation as to the appropriate type of resin that will be used, but my guess is something along the lines of the kind of resin/plastic that Privateer Press use now, or Mantic used for their experimental Revenant Cavalry.
Given the tail off in LotR model sales that has occurred in the last 12+ months, I suspect there is plenty of metal LotR stock still to be hoovered up, and so there is no reason to panic. But just to be on the safe side, if there are any metal models you simply *must* have then it might be prudent to buy them sooner rather than leave the decision for too much longer. Also, don't expect any new models produced for The Hobbit to be in metal.
More discussion on this can be found on Warseer:
http://www.warseer.com/forums/showthread.php?t=298959, and also where I found it first, Frothers:
http://www.frothersunite.com/phpBB2/vie ... sc&start=0