Recently, I've been playing around with Yuuguu which is a non-browser based downloaded chat window. Although the current version (in beta) requires each person to download the software to their own computer and register for a free account to communicate with another Yuuguu user, there are some very interesting components to the software. First, it allows you to co-browse with another user independent of OS (PC to Mac, Mac to PC, Mac to Mac, PC to PC) and using any browser (Safari, Internet Explorer, Firefox...). Also, Yuuguu let's you share your desktop and files with another Yuuguu user. You can even co-edit documents and complete online forms together in real-time. The co-edit feature is a bit sluggish but it works. When connected to another Yuuguu user I have the opportunity to share my desktop and files and so does the other user.
It's not perfect but it does seem to be getting a step closer to what we librarians are ultimately looking for in a virtual reference environment which is to easily communicate with patrons via chat windows embedded in websites that don't require any downloading or registration on the patrons end and can seamlessly co-browse between different operating systems and browsers. Yuuguu is still in beta so it will be interesting to watch how this software develops and what other similar products are coming up with.