Zillow API partners have been receiving important notifications overnight which aims to clarify their API Terms of Use.

Specifically, Zillow is requiring that links to Zillow are "followed" and that developers do not modify the code with a "nofollow" attribute. API partners are required to comply to the new rules by July 15, 2008.

If you publish an API you might want to consider rewiring your own API terms of use to encourage (not force) follow links - the benefit for your own SEO campaigns will be tremendous. If you utilize one of the many APIs publicly available, it might be time to review the terms of use to ensure you are not in violation of such unique SEO-centric policies.