SQL Azure will be rolling out new features over the next few months including MARS support, spatial data, and a 50 GB option. Also available is SQL Azure Labs, where previews of possible enhancements like OData Services will be showcased.
MARS stands for Multiple Active Result Sets. First introduced in SQL Server 2005, it allows multiple simultaneous operations to occur on the same connection. These operations could share a common transaction, but there are strict rules about the order in which queries and DML operations are performed. MARS support for SQL Azure is expected in April.
Geography and geometry types based on the Open Geospatial Consortium standard were added to SQL Server in 2008. These too will be offered in SQL Azure, but not until June.
The last of the promised features is a 50 GB option. Like the one and ten GB options, the 50 GB option will not become widely available until June. However developers needing it sooner can enroll in an early adopter program. Eric Nelson has more information on his blog.
SQL Azure Labs is a proving ground for new SQL Azure features. There are no guarantees that these features will ever make it into the production version, but it does allow developers to offer feedback before the features are backed in. Currently the only feature is OData Service for SQL Azure.