The physical universe, as opposed to something abstract and immaterial, like cyberspace (in the Gibsonesque sense) or anything else that is purely digital. It's used pretty much exclusively (to my knowledge) in this digital/physical dichotomy. The only difference it has from meatspace is that our existence is a bit more dignified : instead of being mere slabs of meat, we're chunks of flesh.

Example : "You'll never see a boxed version of Debian in fleshspace"