Paris Hilton made the CBS News PC Answer Section of their Web page. There's mention of J2ME technology for her Danger Sidekick phone/PDA combo that she had hackers hack into back a month ago (Personally, I think it was probably an inside job at T-Mobile that had nothing to do with her phone).
When it comes down to it, there's nothing like a little common sense for cell phone security, now that these high-end devices have much more of your personal info on them. Lock it with a password (all phones have this feature). And, turn-off Bluetooth when not using it. That's it. Simple. It's not J2ME technology or the phone system that makes the new generation of cell phones vulnerable. It's ditziness of not doing some simple things to make your data safe. Just like locking your car when you leave it in the mall parking lot. Paris should relate to that. :-)