Dimdim has been available as a Moodle integration for several years and is the first conference tool that I cut my teeth on in 2007. It had been a viable open source project and relatively low cost software-as-a-service. Both aspects of it’s business were popular webinar integration tools within the Moodle community. From the official Salesforce/Dimdim notification,
While Dimdim will discontinue supporting the open source code at Sourceforge.net [http://sourceforge.net/projects/dimdim/] it’s possible that other developers could continue to maintain that branch or utilize that code as a foundation for a new open source webinar tool. Unfortunate for the community of users (and more so if anyone made the jump from Wimba/Elluminate to Dimdim in wake of the Blackboard acquisitions last year, there still are several growing and viable open source/low-cost webinar services available.
Two open source alternatives available are*:
Other non-open source alternatives include,
If there are other please post them in the comments.
*While I might suggest looking into each, I cannot and do not endorse either.