Updated RBS Packages are available as part of the SQL Server 2008 R2 August CTP release. This includes the new default FILESTREAM RBS provider along with many other enhancements and bugfixes.
In addition to the new provider, several features were added to the core RBS client libraries. These include asynchronous provider requests, deferred deletion of collections, maintainer optimizations and support for provider specific consistency checks.
Administrators and developers can look forward to significant performance enhancements when these are made available in future CTP releases.