Just like we did with SQL Server 2005 we will be releasing cumulative update packages on regular intervals for SQL Server 2008 too. This package contains all of the SQL Server 2008 hotfixes that have been released since the initial release.
This first package takes SQL Server 2008 from build 1600 to build 1763.
Check this blog by the Microsoft SQL Server Release Services for more details.
Remember to read the "Understanding Incremental Servicing Model for SQL Server" article if you are not yet familiar with this concept.