Some gory details on how the BBC's #microbit
will actually get programmed by the programmer. tl;dr: Web-app compiles program to C++, web service compiles C++ to mbed binary, mbed binary manually(!) copied to USB mounted drive.
Remember when computers used to ship with a programming environment out of the box? Now just installing
the programming environment is so complex that, in 2015, we hide it behind a cloud service.
Also the site contains the following: "The student is prompted to save the ARM binary program to a file, which she then simply drags to the micro:bit mounted drive, which flashes the micro:bit device  with the new program." Apparently, Microsoft don't think men will be able to program it(!)
[For the irony impaired: of course I understand the good intentions behind trying to claim "she" as the "indefinite programmer" pronoun but understanding the use doesn't stop it annoying me any less.]