Thank you for all the advice, everyone!
Unfortunately, the cabinet does not have any other points of access into the top bar portion and all the hinges on the cabinet parts are Soss hinges (i.e. invisible once the doors are closed). There is a drawer that pulls out on one side, but I can't get into the top bar cabinet upon removing this drawer either, can just touch the bottom wall of it. It really is a cool piece. It should be a pretty sweet bar once some light refinishing is done. I've uploaded a few more photos here:
http://imgur.com/a/1UkzMThe first image is the top of the cabinet, with the stuck lock. Through the space between this top cabinet panel and the surrounding portion with the lock, I can see the bolt extending into the top cabinet panel. The space is very narrow, however. Even fitting a thin credit card/paper clip in there is a bit tough.
The second photo is the side door panel (with functioning lock) where the bolt pushes into the slot. I'm assuming the slot on the top cabinet panel is similar.
The next two photos are what the functioning lock looks like from the bottom end (this lock is on a vertical panel and extends downward into the side door panel).
The last photo is a side view of the cabinet (jammed lock on the top center, functioning lock on the side with the open side door panel. And yes, that is a headlamp on the top of the cabinet.

The side view of the functioning lock is the fourth photo down in this album:
http://imgur.com/a/BAUeH If I understand femurat's question correctly, the lock appears to be in a pocket. I don't think there is any way for me to be able to force the lock inward. I think my plan is to head down to my neighborhood locksmith with photos (before lugging the whole piece down there) and see what they would possibly charge to open it and make a new key. If its outrageous, then I will probably pick up a blank key and start impressioning. All else fails, a hacksaw may be possible, but I think the risk of damaging the piece may be too great with that option. Just below where the bolt enters the top cabinet panel, there is a ledge that the panel rests on (so it doesn't fall into the cabinet). Making that cut on the bolt would be a delicate operation. I do have a Dremel saw with very thin blades that may do the trick...but then I worry about sparks. One step at a time! Photos to the locksmith first. Thanks again everyone!