Dimdim, the open source web conferencing application that we've liked and
written about is out in a new
version 4.0. Dimdim is widely regarded for its ability to host online meetings including up to 20 people--for free. The new version adds many new features including letting you record your meetings and share playback URLs. If you have an existing Dimdim account, you'll be automatically upgraded. Here's more on what you get in the new version.