Today I installed SugarChat module for SugarCRM 4.5.0d. Right now it is compatible with this version only.

Install the SugarChat module and upload through Admin->Module Uploader and then this module will be visible in the tabs. Create a chat room and then you can chat with other users who are logged in at that time.

SugarChat allows only text chat. It is really a good module but there are few things that made me to struggle with. It does not refreshes automatically, you have to refresh the page every time to see the responses from other users. Sometimes it is a panic when the page takes time to load up.