PostgreSQL 8.0 was released today, with loads of new features.

Some of the new features include:

• Win32 Native Server Installer - no more cygwin
• Savepoints - Savepoints allow specific parts of a transaction to be aborted without affecting the remainder of the transaction.
• Point-In-Time Recovery - there was no way to recover from disk drive failure except to restore from a previous backup or use a standby replication server. Point-in-time recovery allows continuous backup of the server. You can recover either to the point of failure or to some transaction in the past.
• Tablespaces - Tablespaces allow administrators to select the file systems used for storage of tables, indexes, and entire databases

I use PostgreSQL in production (this blog is even running on it), and its a great DB server. If your looking for an open source RDBMS that can match features with SQL Server, and Oracle then you should take a look at PostgreSQL. MySQL is working on these feature, but PG has had things like views and stored procedures for years, they are well tested and solid.