Microsoft BizTalk Server Pricing and Licensing Overview
The BizTalk Server 2010 editions are designed to address customers' diverse needs. Customers interested in building connecting their business applications or bridge gap between their business partners can leverage BizTalk Server. BizTalk Server also provides RFID and Sensor platform along with adapters to various Line of business applications.
BizTalk can be used in the development of Service Oriented Architecture (SOA), Business Process Management (BPM) scenarios. To address a range of scenarios, the product is now offered four core editions: Enterprise, Standard, Branch, and Developer. BizTalk Server 2010 Enterprise Edition, Standard Edition, and Branch Edition are all licensed on a per processor basis. A processor license is required for each processor on which you install any component of BizTalk Server (for example, BizTalk Server Rules Engine). However, certain tools and components may be installed on a separate device without acquiring a processor license. These components are explained in more detail in the BizTalk Server 2010 Pricing and Licensing Frequently Asked Questions.
You can find the price comparison chart here