Among other improvements, here's a list of possible inclusions. These are merely my own opinions, there are no links for documentation on this information, none of them have been verified/validated by anyone in the world ...simply put, take these with a grain of salt (although a pretty large grain, if you prefer).
xxx8226; Device Diagnostic Application - An application that will run diagnostics and report some of the following: IP Address, Network, Radio Access, Signal Level, Application Version, Free File Space, Radio Data Activation, Platform, etc. This will be various tests, including Self-Email, Self-PIN, etc. Reports/tests can be saved, emailed, PIN'd, etc.
xxx8226; Camera (8100-only, currently) will support storage to Device Memory or Media Card; Picture sizes will Large, Medium, or Small; Picture quality will be Normal, Fine, or Superfine; Zoom Mode can be set to On/Off; Flash can be set to On, Off or Automatic (leaving on will cause battery drain); White Balance can be set to Automatic, Sunny, Cloudy, Night, Indoor, Incandescent, or Flourescents.
xxx8226; Camera (8100-only, currently) can be disabled by IT Policy, for security-concerned administrators and companies.
xxx8226; Location Based Services (LBS) - as Dawg mentioned on the 8100 thread, GPS navigation with turn-by-turn directions
xxx8226; File Explorer - Ability to browse files on the handheld in designated user database areas; create folders, etc.
xxx8226; Wireless Software Upgrade Control Application - No clue what this is, but it sounds interesting, doesn't it?
xxx8226; Built-in Security Monitor - Will have the ability to wipe the device or take other actions on various triggers, such as data tampering.
xxx8226; Setup Wizards - GUI interface to setup various aspects of the handheld.
xxx8226; Voice Notes - Interactive voice recorder for taking and sending messages/notes.
xxx8226; Voice Activated Dialing - Self-explanatory; see 'excited-wet-his-pants' notes from BG in the 8100 thread; appears to be supported ONLY in North America (Mexico/Spanish, United States/English, Canada/French).
xxx8226; myFaves - Not really sure on this one either; appears to be some sort of community/IM-type Buddy List (could be WAY off on this assumption though); information is stored on a third-party server (icons, address book information, phone numbers, etc).
xxx8226; Updated BlackBerry Messenger w/ new interface and appearance
xxx8226; WAV file support for email attachments