Given an MLS#, I'd like to get an XML document with details about the listing, like address, price and such. Not a NAR or CREA member. Mostly interested in North American rental property listing data.
If you're an NAR member, you can utilize their Internet Data Exchange (IDX) system, but it isn't available to non-members.
Multiple Listing Service (MLS) - a system in the USA and Canada for real estate
For mls.ca (Canadian system), here's an interesting perspective (posted 2008-08-21) on it's availability to the public:
Canadian Realtor Data Cartel excerpt:
Realtors as consultants would also mean they could relax their data cartel, also known as the Multiple Listings Service. This database of sale listings has two faces. Firstly, a private view for realtors only, which shows real-time listings with full details about the homes. The MLS also provides a public view of the data but listings there are time-delayed (often by days) and don't provide all useful details such as direction house is facing, wether the basement is developed, etc in a searchable format. Only recently, due to repeated better offerings that were sued out of existence by the cartel, has the MLS even added interactive maps. They still time-delay public listings and hide many useful details.