"A lot of sh1t" doesn't mean anything or everything. I can do a lot of sh1t either, f.e. throwing keyboards out of a window, or use pencils to perforate, err, point on things on-screen on flat displays.

As probably nobody "in the public" has access to (both) Surface(s) yet, time will tell. Obviously, it was determined that WinRT (i.e. ARM-based) tablets / devices will definitely be SecureBoot-enabled; whereas x86-based ones shall be modifiable - still enabled, but the lock can be switched off as it seems:

"Hardware makers who choose the optional Microsoft Certification will be required to implement UEFI. Microsoft will also require that manufacturers offer the ability to turn off the secure boot feature on x86 hardware, but they must not offer such an option on ARM hardware. No mandate is made regarding the installation of third-party certificates that would enable running alternate software."

Note that the Surface Pro integrates an i5 processor. With high probability, you can install GRUB or whatever; and using unetbootin to fill the integrated flash with bits resembling an alternate OS.

EDIT:: i don't know if GRUB etc. will be recognized as "verified OS loaders", and if platform keys will be used by different OSes. Refer to the ZDnet articles.

It surely will. But it is a question if the degree of change may be noticeable, or not. :P