Maybe not on comments, but you can definitely segment your friends on Facebook itself.
If you put your friends into groups, you can click the lock next to the Share button and customize which people or groups get to see the status update.
It's a pain in the ass, but it's definitely possible.
This does not seem to be true. When I click the lock and choose "Customize" I am given a text box in which I can type the names of individual friends, one by one. Groups don't seem to have much -- anything? -- to do with it.
So, yes, you're right, but I'd revise "it's a pain in the ass" to "it's an epic pain in the ass."
If you put your friends into groups, you can click the lock next to the Share button and customize which people or groups get to see the status update.
It's a pain in the ass, but it's definitely possible.