Bitwise Instant Messenger offers encrypted P2P chat communications, you can use this tool for voice over IP chat, group tab conversations, talking with multiple people at once, whitelisting users able to contact you and offline messaging where everything is forwarded to your email (accessible with a mobile phone?), skinning, emoticons and even a whiteboard that can be shared in between users to draw and paint diagrams in real time, the whiteboard will automatically open up when someone starts drawing.
Encryption can not be turned off, this is good practise as it stops irresponsible users, when creating the password Bitwise will reject it if someone chooses a common dictionary word, often used by password crackers. Encryption consists of 128bit Blowfish and a RSA key of 512bits in the free version, the paid version adds key strength, people with serious opponents will have to upgrade, encryption defaults are a little poor. File transfers and voice over IP calls are also encrypted, VoIP works on dial-up thanks to a compression algorithm called Speex reducing bandwidth usage. Calls are not routed through any third party server they run via a direct connection, you can create conferences for multiple people, they will be able to join by invitation only and the chat can be logged to your hard drive.
The part I would watch out for privacy wise is that you are using Bitwise own server to login, this means access logs (no contents), and the people you are talking with can get your IP address, you can’t have a P2P chat without an IP as the software wouldn’t know where to send the data, you will need a valid email address to open an account with Bitwise. This tool is not an anonymous IM but a private one. All other mainstream messengers also fall foul of these problems with central server logs recording who is logging in with timestamps and exposing the user IP in P2P. The main advantage of this messenger is encryption stopping third party eavesdroppers, the paid version allows you to use your own RSA encryption keys.
The software is available in multiple languages for Windows, Mac and Linux, there isn’t a portable version of Bitwise IM but there are instructions on the help pages on how to easily create it by copying settings and Windows files to an external memory card or drive. There are no public chatrooms, you can only communicate with people you already know or those who have chosen to make their information public in the directory, there is no webcam support either and you won’t be able to chat with MSN, ICQ or Yahoo messenger users, Bitwise has its own protocol.
I can see this IM being fine for a small business setting up a no distractions secure messenger, specially indicated for those who only want an IM for sensitive work and do not need anonymity in between members. If you would like to rescind from a third party central server for IM then use Hamachi or Comodo Unite.