I just posted Arduino 0021 to the download page. It’s a quick release to fix the problems with analogWrite() (PWM) on pins 9 and 10 on the Arduino Uno.
This release also includes Linux (32-bit) support for the Uno and Mega 2560 (as well as the rest of the Arduino boards). The RXTX library was patched to support /dev/ttyACM* devices (which is what the ATmega8U2 on the Uno and Mega 2560 shows up as). Apologies for the delay in getting this out. Please note that there’s some weirdness when uploading to an Uno or Mega 2560 that’s running a program that sends data over the serial port. I’m not sure exactly what’s going on, but if you unplug and replug your board, or hold down the reset button, or manually delete the ACM0 lock file in /var/lock, you should be able to get it to work. Any suggestions on how to fix this properly are welcome.
Update: A 64-bit Linux version and a source archive for Arduino 0021 are now up on the download page (under “also available from Arduino.cc”).