Consider the following scenario: you have a tested BizTalk Orchestration that effectively takes a parameter (say, a message identifier) and returns the message from a database for consumption. Now you want to expose a WCF Service for consumers of that orchestration to use. While you could design a SOAP based interface, a simple RESTful interface that accepts a GET verb would do the trick more elegantly (and in a way that would be much easier for clients to work with). It also may meet a requirement when you already have clients that expect a RESTful interface for data retrieval.
There’s plenty out there on handling REST GET requests using BizTalk Orchestrations as a consumer:
Unfortunately, the same can’t quite be said about handling REST GET requests as a provider; there are resources:
…but this side of the equation tends to focus on POST and PUT…