There's an app called craigspro that provides a much better interface to Craigslist on mobile devices. They claim that the app is Officially Licensed by Craigslist, but I thought Craigslist never licensed their content, and the only thing I can find on the subject in the terms of use is this:

Any copying, aggregation, display, distribution, performance or derivative use of craigslist or any content posted on craigslist whether done directly or through intermediaries (including but not limited to by means of spiders, robots, crawlers, scrapers, framing, iframes or RSS feeds) is prohibited. As a limited exception, general purpose Internet search engines and noncommercial public archives will be entitled to access craigslist without individual written agreements executed with CL that specifically authorize an exception to this prohibition if ...

Does anyone know how do get a "written agreement" with Craigslist, and roughly what their terms would be? Do they charge a fee, or just check that you're not evil? I'll try next with Craigslist directly, but I'd like to get a sense of the landscape before stumbling in.