Developers using the Windows Azure CTP have been asking about the roadmap for SQL Data Services. Today the team detailed some important announcements most importantly they will deliver full relational database capabilities delivered as a service.
Also note that SDS will stop supporting the current ACE (Authority, Container, Entity) data model and developer experience since Windows Azure storage has a similar data model. Windows Azure tables provide structured storage as a set of entities, which contain a set of properties. An application can manipulate the entities and query over any of the properties stored in a Table. More information on Windows Azure tables here.
Read the details of the SDS announcement at the team blog.