The system development world is excited about Unikernels lately. In short, Unikernels are applications that are compiled to a self-contained, bootable operating system rather than a process in an existing operating system.
Is there any theoretical problem or practical caveat for compiling a Unikernel from a garbage-collected language like Google's Go?
There is no theoretical problem or practical caveat for compiling a unikernel from a garbage-collected language. In fact, one of the first unikernel projects, MirageOS, is a framework for developing unikernels in OCaml, a functional programming language with a garbage collector. Language-specific unikernel frameworks for Haskell, HaLVM, and Erlang/OTP, LING, also exist and have growing user communities. There are even golang-based unikernel projects like Clive.
Browse the unikernel.org projects list for a more comprehensive and up-to-date list of the exploding unikernel project space.