Fred modified his MCP adapter to fit the new retina model as well as the older model. - "I did it because it seemed like the obvious solution, and because I thought that it was absurd that Apple had made such a near-sighted design decision In moving to the Magsafe 2. I also kinda hate dongles and adaptors. The universal solution is much nicer.
I started with a little machining, however the metal plug end is so small that it’s pretty hard to grab with the vice. I removed a little material, but after a couple dicey passes (and sliiightly mashing the plug) I resorted to doing it by hand. With a file. It isn’t pretty, and it took forever, but it does work. It’s a little sloppy in the original Magsafe jack, but it charges no problem in both."