While we have yet to see any official release announcement, if you browse the PostgreSQL FTP server you can now find the final packages for PostgreSQL 9.0.0. This major update to PostgreSQL brings easy-to-use replication, mass permission-changing, anonymous code blocks, enhanced stored procedure support, exclusion constraints, deferrable unique constraints, and a variety of other enhancements.
More details concerning PostgreSQL 9.0 can be found within their 9.0 developer documentation
. Those wanting to snatch the source-code to PostgreSQL 9.0.0 can find it in this FTP directory