At the present time, you can select the Arduino package in the repos, but it won't actually install due to a dependency problem for powerpc only.

This is the *wrong way* but if you grab librxtx-java_2.2pre2-8_powerpc.deb from Debian and install that, then Arduino will install from Synaptic fine. And it works fine (version is a bit stale).

(Random Tip change .arduino/preferences.txt to set editor.antialias=true)