According to the official announcement, also the date mentioned by Ryan Ozimek on Joomla! Day Poland 2012 - Joomla 3.0 is ready to download & install.
Joomla! release cycle 2011-2014
As most people know, version 3.0 is the next major release of Joomla after the huge success of version 2.5. Joomla 3.0 is just a bridge to 3.5, and support will end 30 days after 3.1 sees the light of day. Because the changes from Joomla 2.5 to 3.0 are large, there is no core upgrade path, this is indeed a migration process.
As you can see Joomla 2.5 is sttill the preferred platform for a vast majority of the users - firstly It's stable and secure version , secondly huge number of the extensions support Joomla 2.5 and finally it's supported till April 2013. But remember that Joomla 3.0 is a first fully mobile & responsive CMS release of the Joomla project. Version 3 is recommended for more experienced users and developers.
The most noticeable difference is the new administrator template, named Isis, now it has full mobile support. Joomla 3.0 uses Twitter Bootstrap.
Joomla 3.0 System requirements
To install and run Joomla 3.0 your web host must meet certain minimum requirements:
- PHP 5.3.1 or higher
- MySQL 5.1 or higher
- PostgreSQL 8.3.18 or higher
This means you need to ensure your host supports these before taking the plunge. Fortunately, most of the popular web hosts meet these requirements.
- Disk space - 10 Megabytes for a minimum base installation, at least 100 MB with many contributed components, modules and templates, and more for database content, media, documents, images, backups and other files.
Download Joomla 3.0
Joomla 3.0 Stable Full Package - download