As a new generation of database engine, Microsoft SQL Server 2008 is architecturally enhanced to provide a trusted, productive, and intelligent data platform for most demanding mission-critical applications.
A lot of cool features have been revealed, one of them is FILESTREAM, which can be used to provide better support for SharePoint Document Libraries. Therefore, large files can be efficiently managed by SharePoint, but no longer need to be physically stored in the SQL database.
According to MSDN, FILESTREAM "allows structured data to be stored in the database and associated unstructured (i.e., BLOB) data to be stored directly in the NTFS file system. You can then access the BLOB data through the high-performance Win32 streaming APIs, rather than having to pay the performance penalty of accessing BLOB data through SQL Server."
Unfortunately, MOSS 2007 currently does not provide any official support on this feature of SQL Server 2008.
However, the good point is: "Instead of being a completely new data type, FILESTREAM is a storage attribute of the existing varbinary (max) data type. FILESTREAM preserves the majority of the existing behavior of the varbinary (max) data type. It alters how the BLOB data is stored – in the file system rather than in the SQL Server data files."
"Because FILESTREAM is implemented as a varbinary (max) column and integrated directly into the database engine, most SQL Server management tools and functions work without modification for FILESTREAM data." Thus, it is technically possible to use FILESTREAM with current version of SharePoint.
Actually, a .NET Architect in Rome, Vincenzo Tenisci, just posted his solution for this last week.
BLOG: SQL 2008 FILESTREAM and SharePoint Document Libraries
It is worth giving a try.
For more information about managing unstructured data with SQL Server, download the white paper from here.