747b0392__5_1___Postgres_OnLine_Journal__Microsoft_SQL_Server_2008
[Feature] Computed Columns [MySQL 5.1] No - but looks like its slated for future release [PostgreSQL 8.4] No - but PostgreSQL has functional indexes so just use a view. [Microsoft SQL Server 2008] 
Yes - but we still like using Views more except when we really need the computed column indexed and often we just do triggers. Computed columns are of very limited use since they can't hold roll-ups.
Cross Compare of PostgreSQL 8.4, SQL Server 2008, MySQL 5.1 - Postgres OnLine Journal
Microsoft SQL Server 2008