MPIDE in Ubuntu 12.04 LTS x64:

After having Ubuntu installed and update all the packages using:

$ sudo apt-get update

Open a terminal, execute:

$ sudo apt-get install openjdk-7-jdk librxtx-java ia32-libs libreadline6:i386 libelf1:i386 gcc-avr    
$ sudo usermod -aG dialout my_user_name
   

3. Logout, log back in.

4. Open a terminal, execute:

$ wget https://github.com/downloads/chipKIT32/chipKIT32-MAX/mpide-0023-linux32-20121013-test.tgz
$ tar xvzf mpide-0023-linux32-20121013-test.tgz
$ ./mpide-0023-linux32-20111221/mpide

5. Connect your chipKIT and use the IDE as you would normally.