All four emulators made by "yongzh" works flawlessly on my HTC Dream device.
Not only this developper prooved that emulation over Java-based android is feasible, each of them were implemented with ease of use and quality in mind.

Notes:

- Sound is not choppy
- Emulation is smooth (no lag at all for all roms I sent to it)
- Customizable keys makes it easy to use the keyboard as if you have a real gamepad
- Interface for save state could not be easier: when you open the rom, it automatically detects if any .SAV file is in the same folder of the rom, and then ask if you want to resume.
- Picking roms among a folder containing hundreds of them is easy: just input the first few letters of the rom name and it's automatically filtered.
- ZIP roms are automatically handled.

In one word : Wow !