Today, scientific meetings in virtual environments or platforms like Second Life are still unusual enough to merit notice, though such meetings are less focused on the medium or technology, and more focused on science.
Will virtual meetings replace such established events as annual conferences? No. What will happen in the next decade, however, is that virtual environments will shift from being things that users log into from time to time for meetings or salons, and will become more like IM: something that's always on, and that users turn to when needed.