It still requires scrapping to discover the thread ids though does it not?
I guess there's mime/url encoding or whatever, but that's hardly an issue.
Pipes/YQL seems not to have been banned yet, so getting 4chan data back wrapped in a callback for nothing-but-front-end hacks seems doable. Also along those lines: it'd be super-awesome if the API would take ifModifiedSince as a query parameter and not just in headers.