Nothing official has been announced with regards to an update date. To answer your original question, the update will include:
- Android 2.1 OS (Main enhancements: Bluetooth File transfer, New Market App, Native support for multiple GMail accounts)
- Updated HTC Sense (New Graphics)
- New FriendStream Widget (Like Peep, but with Facebook status updates as well)
- Newer version of people widget
- Update browser with advanced search, copy & paste and translate functions, along with and update version of Flash Lite
- Full Screen Weather animations
- Many apps are for Android 1.6 or later (Google Goggles, Google Maps with Buzz e.t.c), these will become available to the Hero.
- Speed and performance increase across the system
- OpenGL ES 2.0
- Improved colour depth of the screen (65k vs. 262k)
As far as I know the keyboard won't change from what you already have (although performance should be improved).