here's what i did to get the arduino running on 
linux (ubuntu dapper). basically, i just followed the 
guide on the arduino site
( http://www.arduino.cc/playground/Linux/Debian ) with a few
clarifications/additions (j2re and j2sdk depend on xlibs which 
needs to be installed manually since it has become a virtual 
package in the dapper repositories):

 0. Install xlibs 6.8.2:
     wget
http://www.chorse.org/junkroom/xlibs-dummy/xlibs_6.8.2-77_all.deb
    sudo dpkg -i xlibs_6.8.2-77_all.deb

     1. Add the "blackdown" repository for your java apps: 
        sudo vi /etc/apt/sources.list
        Insert the following line:
        deb ftp://ftp.easynet.be/blackdown/debian unstable main
        non-free 
        
     2. Update software index: 
        sudo apt-get update 
        
     3. Install subversion, AVR tools, and Java stuff: 
        sudo apt-get install subversion gcc-avr avr-libc uisp jikes
        j2re1.4 j2sdk1.4 
        
     4. Check out the Source for the Arduino environment (IDE): 
        mkdir Arduino 
        cd Arduino 
        svn checkout svn://svn.berlios.de/arduino/trunk 
        
     5. Setup your Java and AVR environment variables so that the build
        can do its work: 
        export
        CLASSPATH=/usr/lib/j2se/1.4/bin:/usr/lib/j2se/1.4/jre/lib/rt.jar 
        export DIRAVR=/usr 
        
     6. Now we can build the Arduino IDE! 
        cd trunk/build/linux/ 
        ./make.sh 
        There will be some warnings but it should be okay. 
        
     7. Plug in and turn on your Arduino Board. 
        
     8. Arduino Should now be working. To run it type: 
        ./run.sh  
        
     9. Choose your serial device (On my kernel 2.6.15,
        its /dev/ttyUSB0): 
        Tools -> Serial Port -> /dev/ttyUSB0

-Graham