Ubuntu Linux: yes, it rocks!
I have been using Ubuntu Linux on both PowerPC (dual booting a Mac) and an Intel based PC. For Java developers, Ubuntu on an Intel PC is a better experience (just get Sun's JDK 1.5 as a tar distribution, un-tar it where ever, set JAVA/bin in PATH and set JAVA_HOME) where as for the PowerPC you need to get IBM's JDK 1.4.2 distribution - but that works great, if a little more work to install. If you use IntelliJ on PowerPC, set the -Didea.no.jdk.check=true option because IntelliJ wants JDK 1.4_04.
Ubuntu, except for a few development tools, does a great job setting up by default what most people need (firewall, OpenOffice.org, Mozilla Firebird, etc.)