Interestingly, one of the Linux variants involved was much less offended, and "worked" as long as you didn't try to actually touch the disc. Running stuff like "cat" and "ls" even continued to work, presumably because I'd already run them recently and so they were cached. The other linux variant, however, was far more offended and limited me to just bash. Specifically, those portions of bash that were currently loaded into memory. And while the first remounted everything read-only when the SAN came back, the second refused to believe the reappearance of the SAN and wouldn't even let me log in at a real console. For added fun, Ctrl+Alt+Del had no effect because, rather than sending a command to the kernel as in Windows, under Linux merely causes /bin/shutdown to be run.
To be fair I've no idea how Windows would hold up in a similar situation, although I did once uninstall the IDE controller drivers for the C: drive, and while that drive did vanish from the system nothing spectacular happened as a result. Even Internet Explorer continued to work, although stylesheets stopped being applied, and I could even do a controlled shutdown without anything being able to write to C:. Possibly enough of the driver remained to let the kernel speak to the disk, even if it wouldn't admit so.