tutorial: hello world sample program won't compile

[fsouza]

% rustc --version
rustc 0.3.1
host: x86_64-apple-darwin
% cat > hello.rs
fn main(args: ~[~str]) {
    io::println(~"hello world from '" + args[0] + ~"'!");
}
^D
% rustc hello.rs
hello.rs:2:40: 2:46 error: mismatched types: expected `str/&<R0>` but found `~str` (str/&<R0> vs ~-ptr)
hello.rs:2     io::println(~"hello world from '" + args[0] + ~"'!");
                                                   ^~~~~~
hello.rs:2:50: 2:55 error: mismatched types: expected `str/&<R1>` but found `~str` (str/&<R1> vs ~-ptr)
hello.rs:2     io::println(~"hello world from '" + args[0] + ~"'!");
                                                             ^~~~~
hello.rs:1:0: 3:1 error: Wrong type in main function: found `extern fn(~[~str])`, expecting `extern fn(~[str]) -> ()` or `extern fn() -> ()`
hello.rs:1 fn main(args: ~[~str]) {
hello.rs:2     io::println(~"hello world from '" + args[0] + ~"'!");
hello.rs:3 }
error: aborting due to 3 previous errors