Here's some of the marketing stuff...
Revolutionary Voice Quality The SoundPoint IP 650 is the first IP phone to use Polycom’s revolutionary HD Voice technology that delivers voice communications of life-like richness and clarity.
Advanced Features and Applications The phone’s SIP 2.0 software fully supports Microsoft Live Communications Server 2005 for telephony and presence, and integrates with Microsoft Office Communicator instant messenger client. The SoundPoint IP 650 features a USB port for future applications.
Enhanced Call Handling Capabilities The SoundPoint IP 650 accommodates 6 lines in a standalone mode and up to 12 lines when equipped with SoundPoint IP Expansion Modules, as an attendant console. The phone supports shared call / bridged line appearances as well as busy lamp field (BLF) functionality that enables phone attendants to monitor and manage calls more efficiently.
Expandability When equipped with up to three SoundPoint IP Expansion Modules, the SoundPoint IP 650 delivers the advanced call handling capabilities and enhanced user interface of a high-performance attendant console. (note, haven't seen the updated expansion modules yet... I assume they will be backlit as the new phone is)
Intuitive User Interface The SoundPoint IP 650 delivers all of its capabilities through an intuitive user interface, featuring a high-quality backlit 320x160 graphical grayscale LCD display, an easy-to-navigate menu, and a combination of dedicated keys and context-sensitive soft keys for one-button access to essential telephony features.