DotNetNuke 3.1.0 is now released. It can be downloaded from www.dotnetnuke.com
Read the Documentation
..\Documentation\Public\DotNetNuke Installation Guide.doc
If you are upgrading from 3.0.13 you must read carefully the section on Configuring web.config for Upgrade.
Before proceeding any further, make a back-up copy of your web.config file.