Maybe I am just being special, but I cannot seem to make the rent stuff work.

2 things really.:

1. When running PS, as the only plugin on a craftbukkit server (beta 1.4.6 r0.3). Attemping to use any of the sell/share/rent options, I receive the following error: "Cannot make a field sign that is not attached to a field"
   This happens whether the sign is placed directly on the side of the pstone or on top, or even below. Anyway help would be appreciated. Is there a flag I need to add to a stone to say that it can be rented? The only mention of 'rent' in the config is for logging purposes.
2. When using PS in conjunction with Essentials you receive a message from Essentials saying that the sign was malformed unless PS is on. For me I use OFF unless SHIFT. I cannot remember the option name right now. But shouldnt the sign placement always work regardless of PS on?
   When you do follow 'sell' technique, essentials takes over. Even if PS is on. Perhaps you should use an alternate key word for sell/buy

Messages were mixed up, it would say the field is missing when really you had a malformed sign, and would say the sign was malformed really when you would place a sign on a block that was not a field. I fixed this.

Regarding the [buy], [rent]. and [shared] tags, you can change those on the language.yml.