Well if it's low level stuff (like screwing with the kernel) that you're after, pretty much anything that can write arbitrary binary data to a file pointer will work provided it's run with sufficient privileges. Hell, you *could* do it in PHP if you really, really, really, really wanted to.
That's true. I heard someone mention somewhere writing a virus in PHP. I forget what permissions PHP runs with though. I guess it runs under whatever apache, or IIS, is set to. I think it's some sort of web user. I'm not sure if you could escalate permissions with PHP though. I don't know. I'm sure some people have PHP running as root.