Joomla debuts 1.6 Beta upgrade with an array of added WCM capacities such as:

1. Advanced Access Control System: Version 1.6 changes the fixed group and fixed access level limitations of Joomla. Here you can enjoy the liberty to have any number of Groups, Access Levels and can assign your users to multiple groups. The permissions structure has changed for dynamic projects simplification.
2. Sections eliminated: 1.6 Beta eliminates the binding of categories, but you can have a customized category tree. However, the old limitation that one article can only belong to one category still remains.
3. New Form API: Developers can customize the forms making up the back-end with the help of the new form API. You can include your own custom fields in forms such as the content entry form.

There are a few things that you need to keep in mind while using the new version:

1. Joomla 1.5 supported a legacy mode that permitted you to execute extensions meant for older versions. This feature is not available in the Beta upgrade. It is time that individual extension developers upgrade the extensions.
2. Joomla 1.6 requires considerably higher resources in terms of PHP and MySQL. Your host should be capable of supporting the new requirements.

Click here for a detailed read.