I do believe that is exactly what search engines do. Are they breaking copyright?
This is not a simple question. Huge court cases have been fought over this. In general, things that get Google off the hook in these cases:
* Publishers have the ability to opt out of Google
* Where Google creates copies of information from other sites, those copies are provided to uses noncommercially (ie, they don't make more money when you use their cache).
* Google uses DMCA Safe Harbor to avoid liability, which again turns in part on Google honoring opt-out requests from publishers.
* Google's use of the data is transformative, an idea that in part turns on it not being a direct substitute for the original.
These are not generally arguments that bode well for PadMapper, which is effectively trying to compete with Craigslist using Craigslist data and a better interface. Publishers generally want Google to do things differently... but when push comes to shove, they also really want to be in Google's index. The same is not true for PadMapper.
Second, phone numbers are raw facts, but advertisements are not; every advertisement ever has been copyrighted, and a whole 11-figure industry depends on that.
Neural net for CL postings, extract the facts, reformat for your own display...
The question is, will CL now take steps to make the data more "private" (eg, member only, even if free...etc) or will they take steps to re-introduce themselves into a critical step of actionable use (must login for contact details, etc). CL could start to look like an apartment broker, though, if they follow through with this latter approach.
So this is an interesting dynamic to watch how it plays out. It might aso still be interesting to use a-padmapper-like-service, even as a complement to CL service. If I just had to get 1-5 things its no problem. But sorting 200-400? to find 5 is a PITA, because wading CL is increasingly inneficient. Its a discovery issue.
https://chrome.google.com/webstore/detail/omonmigaleaafgpkgo...
http://techcrunch.com/2012/08/01/clmapper-is-a-padmapper-alt...
So the text of a classified ad itself is indeed copyrightable, but the mere fact that a house at 123 Some Avenue is for rent for $1,000 per month is not. Having learned of that fact from a copyrighted work, and in the absence of an NDA or something similar, you are free to disseminate that fact as you like.
It will be very interesting to see how this plays out.