Is your company using MS Lync as a chat/communication service? You can connect to it with Pidgin using the SIPE plugin. Text-chat and file-transfers work, but I havn’t found a way to get audio and video conversations to work under Fedora 17, unfortunately.
One tip: If you see this error in Pidgin:
Web ticket . . . → Read More: Using a Pidgin SIPE account to connect to MS Lync