some suggestions about security logging:
IP Logging
ip's aren't in the server log anymore. can they be in it again? it makes it alot harder to track players accross different usernames/ip's if thiers no long term ip log. and in-game ip showing command wont work since they only show the last used ip address.
Name Change / username-character logging
need a way to link in-game character names to the login name. the server log shows the login name only. thiers nothing to record what character name a player uses or what they change it too. thiers already been an issue on sabrada where a player changed thier name, cursed at others, racially insulted players, and even tricked several new players into *suicide-ing, and then changed thier name back again. they got away free since thiers no way at all to find out who it was that was doing it.
Investment Logging
recent issues of players getting rich fast and via cheating has me searching threw the logs for gives, sales, etc. but something i just noticed is that a 1s baught/sold store/other business could easily be used to transfer an invested 1400s from a friend made cheat account to a regular account with little proof besides the building sale/buy
Better Security logging in the server.log file (Done 0.46.9)
ah, i hadnt actually taken out the loggin of join info.. just made it optional and forgot to add the option dialog to turn it on 
In Server 0.46.9
Server Menu -> Options -> Log Files
now lets you control which things are or aren't logged.
All the old player join info is now available and their username is displayed alongside the nick used.
The amount of investment in buildings is also logged now, when the 'Building Ownership changes' option is enabled.
The ID/IP trade security is applied in the situation you describe, so unless the player has really gone out of their way to evade the system, they won't be able to purchase the invested building from the 'fake' character.
Just a reminder how the trade security is controlled (for the benefit of new world owners particularly)..
*settings -> Economy -> Security Level
0 - default. Players are not allowed to trade* with other characters sharing the same user ID or IP
1 - Same as 0 atm.
2 - Players are not allowed to trade with other characters with the same user ID, or if the first 3 parts of their IP match.
3 - Players are not allowed to trade with other characters with the same user ID, or if the first 2 parts of their IP match.
4 - Same as 3, but in addition buildings cannot be put for sale for less than the 'jehovah building sale price' defined in the economy settings
50 - (New to 46.9) - No trade security.. anyone can trade with anyone, even multichars or people on the same IP.
* 'trade' as used here implies all transactions between characters - buying a building from someone, buying goods from someone's building, giving cash to someone etc.
Remember, None of the security levels will stop a player creating multiple characters and trading with themselves if they're determined to - many ppl have a spare PC and a spare dialup connection with a totally different ip range that its impossible to track against. You should keep this in mind when designing any economy world - particularly with regard to start cash amounts... A high start cash will make abusing the trading system much more worthwhile to those determined to cheat.
In Server 0.46.9
Server Menu -> Options -> Log Files
now lets you control which things are or aren't logged.
All the old player join info is now available and their username is displayed alongside the nick used.
The amount of investment in buildings is also logged now, when the 'Building Ownership changes' option is enabled.
The ID/IP trade security is applied in the situation you describe, so unless the player has really gone out of their way to evade the system, they won't be able to purchase the invested building from the 'fake' character.
Just a reminder how the trade security is controlled (for the benefit of new world owners particularly)..
*settings -> Economy -> Security Level
0 - default. Players are not allowed to trade* with other characters sharing the same user ID or IP
1 - Same as 0 atm.
2 - Players are not allowed to trade with other characters with the same user ID, or if the first 3 parts of their IP match.
3 - Players are not allowed to trade with other characters with the same user ID, or if the first 2 parts of their IP match.
4 - Same as 3, but in addition buildings cannot be put for sale for less than the 'jehovah building sale price' defined in the economy settings
50 - (New to 46.9) - No trade security.. anyone can trade with anyone, even multichars or people on the same IP.
* 'trade' as used here implies all transactions between characters - buying a building from someone, buying goods from someone's building, giving cash to someone etc.
Remember, None of the security levels will stop a player creating multiple characters and trading with themselves if they're determined to - many ppl have a spare PC and a spare dialup connection with a totally different ip range that its impossible to track against. You should keep this in mind when designing any economy world - particularly with regard to start cash amounts... A high start cash will make abusing the trading system much more worthwhile to those determined to cheat.