Microsoft announced the trial availability of Web-hosted versions of its popular Exchange and SharePoint collaboration software. The move appears to be a strong declaration of Microsoft's intent to blunt Google's rise in the Software-as-a-Service (SaaS) market.

In a keynote speech kicking off Microsoft's SharePoint Conference in the US, chairman Bill Gates announced the expanded online offerings, which US-based companies can sign up to beta test.

Gates is also expected to announce that more than 100 million SharePoint licenses have been sold, generating a total of US$1 billion for Microsoft.

Online versions of Exchange and SharePoint will be generally available to companies of all sizes in the second half of the year, according to John Betz, a director in the online services group. No prices were disclosed, though Betz said companies that already have Exchange or SharePoint running on their premises will get some credit towards the cost of subscribing to the online service version.

"If you've already invested in the software, the price you'll pay will be less than if you own nothing today," Betz said.

Microsoft will aim for companies with about 50-250 PCs, or 100-500 users. And the services will be targeted to appeal to business IT staff, rather than to try to go around them , as Google has said it is trying to do with its fast-rising Google Apps offering.

"Companies tell us pretty consistently that they want enterprise-grade solutions to meet the challenges they face, and that they are concerned about consumer 'hand-me-downs' forming the basis of their business solutions," Betz said.

Though Microsoft is taking another step towards competing with its own partner ecosystem, the latter insist Redmond's entry into the market will help, not hurt them.

"I truly believe that the rising tide will lift all boats," wrote Ravi Agarwal, CEO of GroupSpark, a provider of hosted applications include Exchange, SharePoint and others, in an e-mail. "Microsoft will bring greater awareness to the market, and when prospective customers look at the Microsoft hosted offering more closely and realize that critical features like BlackBerry Enterprise Server are missing -- they will flock to us."

"I think this will accelerate adoption on Microsoft's, rather than Google's, platform," said Keith McCall, CTO of Azaleos, a maker of managed Exchange server appliances. "That's good for us, since we think any company with more than 250 employees will still want to keep Exchange and other key apps on-premise."

Besides Exchange and SharePoint, Microsoft also plans to offer online versions of its Office Communications Server (OCS) unified communications software and its LiveMeeting web conferencing software, confirmed Betz.