Open source, Web 2.0 collaboration is coming to tax return filers in 2008.

Dimdim, a startup that makes open source software that enables web browser users to share voice, video and presentations in real-time meetings, plans to announce on Jan. 15 that a major tax preparer will use its product to serve customers getting ready to file their IRS returns. In an interview Dec. 17, DD Ganguly, CEO of dimdim, said he could not disclose the name of the tax preparation company before the official announcement.

That word comes as dimdim unveiled on Dec. 20 a partnership with SugarCRM, an open-source maker of customer relationship management software. The deal means dimdim online meetings become a feature available to SugarCRM users. Dimdim says it will use Amazon.com’s Elastic Compute Cloud to support these users’ meetings.

Also this month, dimdim said it would offer its next release under the GNU General Public License (GPL).

Dimdim debuted at the fall DEMO conference in September, where Ganguly declared the company’s intention to usurp the primacy of Cisco Systems’ WebEx meeting application. Since then, dimdim says that 13,000 users have used its free hosted service. Since it became available online earlier this year, 150,000 users have downloaded the open source version of dimdim’s software.

Ganguly said a key aspect of dimdim is that it does not require a software download to use it. He said his team has been working on dimdim over the past couple of years with the idea that they could create a real-time video and collaboration tool to build on earlier innovations that have democratized the Internet, like Hotmail and Skype.

Dimdim is free to consumers. The “community edition” limits online meetings to a low number of attendees. The company also offers a hosted software-as-a-service model for $99 per year, and an enterprise edition.

“DimDim poses a credible challenge to the dominance of WebEx and its peers in the Web conferencing space,” said the organizers of the DEMO conference in a statement. (The DEMO conference organization and CIO.com share the same parent company.) “Free to consumers, the open source-based enterprise edition will be sold and supported at a price disruptive to the license fees of the established players, and will be easily customized and enhanced by the open developer community.”

Dimdim's Presentation at DEMO

Below, DD Ganguly, CEO of dimdim, leads a presentation of the online meeting product at at DEMO in September 2007: