This virus acts as a Trojan horse because it comes in a disguise (although it doesn't open a back door). Liberty is a program that allows you to run Nintendo Game Boy games on the Palm OS. Liberty is shareware, but like all useful shareware it has a corresponding crack that converts it to the full registered version.
The authors of Liberty decided to pay back the pirates by releasing a "counter-crack" for Liberty that was actually a virus. The developers distributed it on IRC. Unfortunately for the pirate, when executed, the Liberty crack virus deletes all applications from the PDA.
This virus can spread both through the desktop and through wireless email. In fact, it may be the first known PDA virus to spread wirelessly in the wild.