There are hooks in most themes and in some places in core that try to handle switching blocks for rtl languages.
Really this is something that would be much better achieved in CSS as not all cases are as clear cut as side-pre and side-post.
Having a CSS solution would certainly be more autonomous and facilitate and easier solution.
With the introduction of bootstrap new possibilities have arisen and certainly if bootstrap makes it to core having a bootstrap solution would be excellent.
Damyon pointed out that there has been discussion (https://github.com/twitter/bootstrap/pull/6409#issuecomment-11725361) in the bootstrap community about this and that there is already a pull request for RTL changes: https://github.com/twitter/bootstrap/pull/6423