As has been said before, balance is the core issue here. I think that Pc stealing should be allowed, but on the same token, retaliation should also be allowed. As has been said, no one really wants this to turn into a PK or a PVP game, but i agree with comments that thieves should be able to steal. Perhaps, a percentile type system, based on the Thiefs stealling skill, and the target\'s observance, or anti-thief skill. A certain percentage is success not caught, another is success and caught, failure not caught, and failure caught. If the thief is caught, the target should be able to retaliate. Because of this, even a skilled thief would think twice before trying to steal from a high level warrior, or an archmage. This is again where the balance comes in. Maybe killing won\'t be the end of it, because i do like the idea mentioned about guards. If someone captures a thief, and brings them to the guards, the theif should probably spend some time in jail. Maybe only a few hours for first offenses, but progressivly more time for each successive offense(this is where the karma idea fits in.) Making someone spend a day or two in jail will make them seriously reconsider stealing.
As for what should be stealable, I dislike the idea that it should be coin only. Thieves should have a maximum that they can steal, and that depends on their skill level. Then, assign all items with monetary values. So your newly aquired sword of deamon-slaying or whatever, would be worth like 1000 circles, making it virtually impossible to steal, by all but the most skilled thiefs. Probably make what is stolen random too, because realistically, a thief doesn\'t open someones pack, look arround for a bit, pick what they want, and leave. Its more of an open, grab something, book-it routine. Also, equiped items shouldn\'t be stealable, namely a sword, shield, or armor. I don\'t think there\'s a thief in the world who could get a suit of plate armor off of someone, or get a sword out of someones hand, without being noticed. Jewlery should be fair game, but the difficulty on it should probably be harder.
To keep everyone from being thieves, the pickpocket skill should be fairly expensive in terms of points. The counter skills should be relatively in-expensive, at least for the first couple levels in it. That way a Newbie can afford to spare a few points to protect themselves a little. Also, by making the counter skills cheap, it allows fighters and mages and such to keep the focus on their primary ability, while being able to protect themselves a bit.
Breaking and entering should be equally limited. Traps, alarms, and whatnot should definately be in. I think it would be amazing to be a thief casing out a house, and then slowly working your way through it, carefully disarming traps and alarms. If ya screw up, as before, the penalty would probably be jail time and or a fine of some kind.
As for other rogue skills, like hide in shadows, poisoning, and disarm traps and such, these should be cheaper, because these are, in most cases, very helpful for teams. I think poisoning weapons is good, but poisoning food should be out, because that definately would yield a good amount of pvp.
All These things together make thieving very difficult, but if successful you can make good gains off of it. Just like real life.
Anyways, that\'s my two cents expressed in an epic post. Keep posting the ideas people.