Ask HN: Tools/Libraries to build a RESTful web service in Python?

The title says it all: we're coming from a Ruby background where Rails worked very nicely, but we are not sure what to use to implement an API for an existing product (Python web app). At first glance, a REST API is not much different from a regular web app, except you serve XML/JSON back instead of HTML, but if one looks closer, you'll see issues like safe parsing of submitted objects, WSDL/WADL generation, etc. Googling doesn't help much: a few projects here and there that look like abandonware, Pylons (our web framework of choice) doesn't really have anything built-in. Thoughts?