Carlos posted some thoughts on Java Emulators:
Java enabled cell phones are becoming available to the masses. I was thrilled to see "Space Invaders" being played on a cell phone at my local electronics store. I thought, there's going to be resurgence of those old arcade and computer games, I still have fond memories of Galaxian, Lode Runner, Castle Wolfenstein, Tetris etc. I predict that a few companies will make some good change reinventing these games for mobile devices.
I was however shocked when I noticed my nephew playing games for Gameboy and Gamegear online. It turns out, many game consoles and older computers have emulators written in Java. What this means, if you have a java enabled device, its no leap to run the thousands of games written decades ago on these devices.
First, those are BOTH kick ass links to have around. Thanks, Carlos.
But I have to say that before you get all excited about old arcade games on your Java enabled phone, you have to realize how woefully underpowered the J2ME spec and the KVM really are. The phones that are all out there now have no sound support (or at least no standard sound API), the KVM doesn't support floating point processes and the phones are generally low in memory (we're talking sizes in Ks) and low in processing power. A Palm Pilot is actually A POWERFUL J2ME container - go download the MIDP for Palm software and try it out and you'll see how underpowered it is. Most phones will be worse.
The only different phone that I've seen lately - and confirmed from your linked list - is the SonyEricsson P800 and Nokia 92XX which both run PersonalJava, which is more a subset of J2SE than a superset of J2ME and thus can do some cooler stuff.