lexipixel - 3:47 am on Jun 26, 2012 (gmt 0)
As noted by blogger Gervase Markham, (one of the first people to publicly post about this change), this is very close to a "Man in the Middle" security attack.
It's obvious they're attempting to route all messages through "@facebook.com" addresses to gain the raw email text, senders names, etc.. all valuable data to profile people with.
Now instead of someone directly emailing you, you'll get a notice from Facebook saying "You have messages waiting" and be forced to login to FB to read them.
IMO, FB is the sleaziest company I've even see on the net.