It's like MSN Messenger or AOL, except that the identities of people on it are guaranteed, and things said on it are effectively contracts. Reuters operate a similar system. There are others too but no-one uses them.
Can you expand? Are identities checked and referenced, or enforced socially like on LinkedIn? When you say things are effectively contracts, I've heard about the very solid principles that some finance people work to - "if we said it then we will stand by it" sort of things - or does Bloomberg step in to arbitrate, or are chats accessible by the employing companies, how are contracts enforced?
Biometricaly secured also. The Bloomberg terminal requires a finger print to log into it. Also its a $20k a year subscription, so you can be pretty certain the people you are talking to are important and who they say they are.
They are "checked" in the sense that ultimately there's a name associated with that expensive login. All chats are logged and available to compliance, regulators, etc. Bloomberg won't arbitrate but they don't have to - everyone knows that if you welshed on a deal, no-one would ever deal with you again. This is the same way that voice calls in banks work too.
That's how the entire financial world works. The trades on the stock market are only a highly organized way to agree to a deal. The money and assets change hand three days later.
The financial world does not rely on iron-clad cryptographic security. It relies on a very well developed system of layers of trust.
Entered the network, manipulated data, created misinformation, use social engineering tricks and tried to control stock pricing. When you have a platform only accessible to the elite, it makes the possibilities extremely tempting.
I know, when the company I worked for in the 90's IPO'd in the dotcom boom, we would talk to our broker over just regular AIM. Nowadays that just seems crazy...