[rcthompson]

    cat >/bin/uname <<EOF
    #!/bin/sh
    echo Linux
    EOF
    chmod +x /bin/uname

[DrJokepu]

I see your point; that being said, I was talking about the system call uname(2), not the command line utility uname(1). It's somewhat more difficult to fake that, you need to know your way around C the very least.