Plesk PowerPack is add-on component that will enhance your Plesk's features with additional powerful tools. PleskPP comes with the following features:
- Application Pack
- SpamAssassin Anti-Spam Software,
- Multi-Level HelpDesk,
- Tomcat (JSP) Support,
- ColdFusionTM Support (license not included),
- MSSQL Server Support
- Language Pack.
That means that by having PowerPack, you can manage those applications within Plesk control panel. For instance, you've installed MSSQL (you can't managed MSSQL on Plesk with the default license), if you have PowerPack license - you can easily manage the databases with Plesk, no need to manage it anymore from SQL Management Studio.