3.1 is the newest update, which is what the xoom got. 3.01 isn't much of anything. I believe 3.01 is just acer's original firmware.
Just so you know...
Android 3.01 Updates
1) Native Browser
- Updates for HTML5 support
- New multi-touch support for JavaScript and plugins
- Updates for overflow scrolling
2) Adobe Flash Player update 10.2
- Hardware accelerated video presentation for H.264
- Deeper integration with the Android browser rendering engine
- Enhanced performance for multi-core tablets
- Automatic soft keyboard support
3) Bug fix that addresses daylight savings time and calendar appointments
4) Updates for USB and Bluetooth
Android 3.1 Updates
- UI refinements
- Connectivity for USB accessories
- Expanded Recent Apps list
- Resizeable Home screen widgets
- Support for external keyboards and pointing devices
- Support for joysticks and gamepads
- Robust Wi-Fi networking
- Enterprise support
- Updated set of standard apps
+ Browser
+ Gallery
+ Calendar
+ Contacts
+ Email
Reference:
"A wise man can learn more from a foolish question than a fool can learn from a wise answer." - Bruce Lee