Shared 3D virtual environments like Second Life can be used for group meetings. I know of three basic approaches. Each requires significantly more infrastructure than the last.
The simplest approach is just to meet in Second Life. This enables you to talk, share slides, and do things together.
The next most complicated approach is to augment a real life meeting with some Second Life participation using Skype as a streaming server. This can be done using items found around the home, but provides an awkward connection.
A true mixed reality event links all locations together fairly well. It requires more equipment and more setup, but allows participants to see, hear, and speak to one another from either real life or Second Life.
An argument for using Web 3D for telepresencing, and some tips on how to do it, are in my slidedeck Using Gaming Platforms for Telepresencing.