Microsoft published a TechNet Wiki that summarizes the sharding technique and highlights the new application modeling best practices for best scalability and economics. Most importantly it focuses on how you can build sharded applications today on SQL Azure.
"Database sharding is a technique of horizontal partitioning data across multiple physical servers to provide application scale-out. SQL Azure combined with database sharding techniques provides for virtually unlimited scalability of data for an application."
Read the full Wiki embedded below: