I built this a few months ago, carrying it around mostly for piece of mind, using it only three times, but it charged my DroidX just fine. Just had a run of power outages and needed it and it failed. I'm getting the same 4.95V on the outer pins as when it worked, but only 1.5V on pins 2 & 3. DroidX recognizes it as a charger, but leaving it idle for an hour there was no increase in battery state. Used to be able to charge it while using it.
In need of some solvent, but I didn't see anything that looked like a short or cold joint.
Being unable to score a gum container at the time I built it, I put it in a custom wood and canvas package. No fear of shorts, but I don't know if I could have cooked something without the metal for a heat sink.