Google is adding a new front to its assault on Microsoft’s software applications business.

The Internet search giant on Wednesday is rolling out a rival to Microsoft’s SharePoint, a program used for collaboration among teams of workers. Google’s program, called Google Sites, will become part of the company’s applications suite, which includes e-mail, calendar, word processing, spreadsheet and presentation software. Like other elements of Google Apps, it will be free and require no installation, maintenance or upgrades.

With Google Sites, the company is taking on what Christopher Liddell, Microsoft’s chief financial officer, said has become a $1 billion a year product. That’s a relatively small, but far from insignificant, portion of Microsoft’s business division whose mainstay Office suite is the No. 1 target of Google Apps. Microsoft’s business division brought in $4.8 billion in the most recent quarter.

Google Sites was built on top of technology created by JotSpot, a startup co-founded by Joe Kraus, who also co-founded Excite, the now defunct Internet 1.0 portal. Google acquired JotSpot, which had developed a set of “wiki,” or collaboration, tools in October of 2006.

The Google Sites software allows groups of users to easily create Web documents that include text, images, videos, spreadsheets and other types of documents. Initially, it will be aimed at business users and is being housed in Google’s enterprise group. “It’s our biggest launch since Apps itself launched,” said David Girouard, vice president and general manager of the enterprise group.

Still, pitching Google Sites to businesses may prove a challenge, at least initially. “There is a lot that Google still has to prove in terms of being a viable enterprise vendor,” said Rob Koplowitz, an analyst with Forrester Research. Many businesses remain leery of putting their applications and data on servers they don’t control, for example. Mr. Koplowitz also noted that while Google Sites will include many of the popular content creation and management tools available in SharePoint, it will not have some of the more complex features that allow a large business to manage information across their entire organization. “They are targeting a subset of the SharePoint functionality,” he said.

Then again, Google Sites will be free.