A avr with hardware USB for faster interfacing like the teensy and avropendous working with the sofware here would strenthen open source community.
Higher speed data logging would be neat...
acsept one of these or merge it into the standard arduino boards.
I have recently integrated Arduino with LUFA to create LUFAduino. It adds Arduino support to LUFA instead of the other way around. It also integrates FreeRTOS so that you can use delays and even multiple loop() statements without interfering with USB functionality.
If interested, please have a look at the code and help me debug it. It will work with any USB AVR that has > 2kbytes of SRAM.