Plesk 8.3 offers you the following new features and enhancements:
Enhancements in Auto-installer
Install or upgrade several SWsoft products at once. For more information, see Plesk Installation Guide.
Single sign-on support
Switch among different SWsoft products without the need to specify a username and password. For more information, see the chapter Setting Up Global Account.
Improved integration of Plesk and Sitebuilder
Manage Sitebuilder from your Plesk control panel without needing to install any additional Sitebuilder Management modules or add-ons. By default, Plesk is installed with Sitebuilder. For more information, see the section Enabling Integration with Sitebuilder.
Licensing and upgrade of site applications
Upgrade site applications available on the server and install license keys for them with a few mouse clicks.
For more information, see the chapter Prepackaging Applications Your Customers Can Use.