After 2 and half years development, the Joomla! 1.5 released now.
It is a long waiting. I will hurry to install this new system to test it and try to migrate my Joomla 1.0 site.
To download it, click here. Download the installation package from the Joomla Code Updated 2013.08.29
Installation Instructions
Fresh Installation
Upgrade Instructions
From Joomla! 1.5 RC4
Migration Instructions
From Joomla! 1.0.x
My suggestion is to try the clean install first. Be familiar with the new user interface, administrator end and template. Then you can see how do you migrate your old one. Or just use the new Joomla 1.5.
I have to say, the Open Source CMS is still the most vitality.