Presentation Server 4.5 is available in several "editions," each with a different set of features. Most people reading this book will probably be using the Platinum edition.
The baseline edition is "Advanced Edition," or "Citrix Presentation Server 4.5, Advanced Edition." Depending on how you purchase it, Advanced edition costs somewhere in the neighborhood of USD $350 per concurrent user.
For about $450 per concurrent user, you can move up to "Enterprise Edition." Enterprise edition adds Application Isolation Environments, Resource Manager, Installation Manager, the Server Health Assistant, and Application Streaming support. (Each of these features will be covered in-depth throughout this book.)
Finally, for about $600 per concurrent user, you get "Platinum Edition." Platinum edition is really like an entire suite of applications as opposed to actual features for Presentation Server. Platinum edition adds support for the Citrix Access Gateway (SSL-VPN) SmartAccess, Citrix Password Manager, and Citrix EdgeSight for application monitoring. We won't cover these products in-depth in this book since they are external products, although we will mention them from the context of how they integrate with Presentation Server.
There are a lot of complexities involving how users with different licenses from different editions connect into various editions of Presentation Server. We'll cover all of that in the licensing chapter of this book.