The Tor Project, the non-profit organization which develops software for online privacy, comes with a messagingclient for Windows, Linux and OS X. The client will be based on the InstantBird messenger, and a first build should be ready end of march.
Although instant messaging applications, as TorChat and BitMessage already make use of the Tor network and a lot of popularity among users of the Tor network, it will probably be no obstacle for Timb. The secure instant messaging must eventually be bundled with the launcher of the Tor Browser Bundle, what the reputation of the program is probably a lot will help.
Tor is a worldwide network of nodes, and the design ensures that the location and the activity of the user, difficult to be out of date. The Tor Browser Bundle contains the software, the communication via the network controls and a custom version of Firefox.