With the upgrade to ECC 6.0 Document Browser and ACL Authorization come as new features in the standard of the Document Management System. Please note that these new functionalities depend on the activation of the EA-PLM Extension. This extension is included in the PLM package in the standard.
ACL Authorizations:
Since the upgrade a new tab is inserted in transactions CV01N, CV02N and CV03N which is called "Authorization". With this tab it is possible to add specific authorizations for this document regarding user or usergroups. The default authorization which is created for the user is "ADMIN" authorization. This means the highest level of authorization for this document. Further possible authorization are for example READ, DELETE, WRITE and so on. 
In transaction SE80 you can check the new package CVEXT which is responsible for the authorizations. The database table which is handling the different authorizations is called DMS_GUID. As this authorization concept is used more common with EasyDMS, the documentation is also situated in the EasyDMS area under SAP ERP Central Component - Cross-Application Components - Document Management - Document Management - Authorization Objects for Documents - Access Management Using Access Control Lists.
Document Browser:
The new Document Browser functionalities should enable the user to navigate more easier within the different document info records. Therefore the new button "Document Select via" was implemented in transaction CV01N, CV02N, CV03N. With this button the user is able to choose between different display behaviours in these DMS transaction. By using the setting "Selection Screen" the well known screen is used and the user has to enter document number, type, part and version to get the document detail view. If the user selects the setting "Browser" the new display behavior is used.
With this new function a navigation tree is displayed like in the Windows Explorer. When the user selects this display behavior for the first time the system asked him to create a so called PRIVATE FOLDER. This is very similar to EasyDMS. In the end there should exist one PRIVATE and one PUBLIC folder. More information could be found in the Online Documentation under SAP ERP Central Component - Cross-Application Components - Document Management - Document Management -Document Browser. 
Thumbnails:
The thumbnail functionality enables the user to display small thumbnails of the originals in transaction CV02N, CV03N and CV04N.
To activate this functionality you have to maintain some necessary customizing entries in transaction SPRO under Cross-Application Components - Document Management - General Data - Set Up Workstation Application for Thumbnails (Images). Here you can maintain the relevant application in relation to specific document types. Please note that it is also very important to maintain a sequence. This sequence controls which filetypes are displayed as thumbnails. Only the first application of this sequence is used as thumbnail picture. In the standard system behavior the fileformats JPG and BMP are supported. For using further formats for thumbnail display, you have to convert them. Under Business Add-Ins (BAdIs) - BAdI: Enhancements for Thumbnails (Images) you will find some BADIs for this conversion.
In transaction CV04N you can switch between the standard result list display or the new display with thumbnails. Therefore the button "Display Document as" was created. With this button the user can choose the new result display with thumbnails.
For implementing a customizing functionality to turn on and off the new tab for ACLs and Document Browser see SAP note 1062939 which explains the necessary steps for this. Since Support Package 11 for Release ERP 2005 is implemented you can just use transaction DCSWI for customizing this new functions.