The following is the wording currently added to the icbit wiki to warn people about practices at that site. Fireball has removed various warnings several dozen times. Any suggestion on wording that might be less offensive to him, while still being accurate, would be appreciated.
https://en.bitcoin.it/wiki/ICBIT− Warning.
There are several reports of dishonest practices at icbit.
The website owner has refused to respond to accusations publicly.−
-These accusations include that contract prices do not trade purely based on bitcoin price movements and speculative pressures, but largely on manipulations and that website management cooperates with, and encourages, these manipulations. This allows larger traders, including the site owner, to effectively strip funds from smaller traders.
There are other ethical issues at icbit as well.
−The owner of icbit has so far refused to answer complaints publicly, he has refused suggestions on how to clean up his site and he has refused to refund money to those who point out unethical practices.
−Please do not invest any money at icbit until you understand the issues raised in the complaints and/or the alleged dishonest practices have been changed. If you are not sure please ask questions in a public forum like bitcointalk.org and do not give any money until all questions are answered to your satisfaction.−