A quick scan of the web will pick up meanings for SSDS:
Yesterday it acquired another meaning SQL Server Data Services
Now in addition to pay as you go phones, hotels (in Japan), Motorway tolls, SSDS is a pay as you go database hosted by Microsoft and as the catchy title suggests is built on SQL Server.
It's essentially there to support the development of flexible web 2.0 applications and so it understands all of the latest in connectivity such as SOAP, REST and LINQ. Both VB and C# programmers and can work with it and it's in its beta form to try now.
Many of the production details are still being worked out, such as how much will it cost, what's the SLA and so on, so join the beta and post tons of feedback on Connect.