747b0392__5_1___Postgres_OnLine_Journal__Microsoft_SQL_Server_2008
[Feature] Access tables from other databases on same server [MySQL 5.1] Yes - db.table, but not easily across servers. Across servers you need Federated storage engine See Rob Wultsch note [PostgreSQL 8.4] Sort of - via Dblink, but much less elegant than MSSQL and MySQL way and much less efficient. Can also access disparate data sources via DBI Link [Microsoft SQL Server 2008] 
Yes - server.db.schema.table, can even access disparate data sources via linked server or open query
Cross Compare of PostgreSQL 8.4, SQL Server 2008, MySQL 5.1 - Postgres OnLine Journal
Microsoft SQL Server 2008