http://www.itsec.it/2012/09/18/uefi-technology-say-hello-to-the-windows-8-bootkit/
PCs/laptops until recently all used a Bios on the motherboard to both control the hardware & start the OS [Windows, *nix etc.] -- this is changing with the UEFI Bios, which still controls hardware, but moves much of the code &/or functions of the user interface & starting the OS from difficult, specialized Assembly language in the firmware to a more universal UEFI Framework written much like any other programming code. In effect this means a nicer Bios GUI, where you might use the mouse etc., have a larger number of options, including things like a *nix OS that will run from the Bios, & because you're no longer limited to a few MB of code flashed to the Bios chip(s), you have much more flexibility, much fewer limitations. [ http://en.wikipedia.org/wiki/Unified_Extensible_Firmware_Interface ]
Win8 has the option for manufacturers to include basically key matching in their Bios code, so if a boot loader doesn't have a matching key it won't start. This should be more secure, though it makes the *nix folks jump through hoops -- not every *nix distribution or version will have some sort of key mechanism available.
While the article doesn't deal with win8's SecureBoot tech itself, it does provide a lot of good info on how UEFI works I think, though it is more on the tech or geeky side of things, & the article does make the point with a proof of concept Bootkit, that UEFI is easier to work with, in theory making things easier for those writing mal-ware.
