You may have see a new SKU of SQL Server 2008 called the “Web Edition”. Here’s the scoop on it:
SQL Server 2008 Web Edition enables hosting companies to provide low cost, highly scalable hosting for developers, SMBs, and consumers, all with a low monthly licensing fee, four CPU support, and no limits on memory and database size for increased scalability. SQL Server Web edition also supports the SQL Server Driver for PHP. As a comparison, SQL Server Express Edition is a free edition of SQL Server ideal for building desktop and small server applications and for re-distribution by ISVs.