The final release of MacPorts 1.8.0 has been made available via the usual methods:

• selfupdate
• DMGs for 10.4, 10.5, and 10.6
• a source tarball
• a tag in subversion

The ChangeLog documents the full list of what has changed since 1.7.0 (which is quite a bit).

You can also read the email announcement for 1.8.0.