Summary:

Online CRM pioneer Salesforce.com continues to back up its ecosystem with its checkbook, this time with an investment in cloud storage provider Box.net. In the past few months, Salesforce.com has made a series of outright acquisitions of Assistly, Radian6, and Heroku.

Marc Benioff, CEO of Salesforce.com, at Net:Work 2010

Marc Benioff, CEO of Salesforce.com, at Net:Work 2010Salesforce.com continues to buy into its ecosystem, this time with an investment in cloud storage provider Box.net.

Sources at both companies confirmed the investment but wouldn’t specify its size. A Salesforce.com source termed that company’s portion of Box.net’s latest round  “a drop in the bucket.” Box.net filed SEC documents for a new $35 million round in early August, although TechCrunch today reported a $50 million round. Box.net is holding off giving a final amount until it officially announces the new funding later this month.

Salesforce.com has opened up its checkbook quite a lot lately to bolster its flagship cloud-based customer relationship management (CRM) and sales force automation (SFA) services as well as the social media and development resources it built around them.

Last week, for example, the company bought Assistly, a developer of “instant customer service help desk” technology that integrates Salesforce.com CRM. That cash deal was worth about $50 million. In March, it bought Radian6 and its social media monitoring technology for $276 million. And late last year, it bought Heroku, a Platform-as-a-Service player, for $212 million.

The Palo Alto, Calif.-based Box.net is also an existing Salesforce.com partner, having already integrated its storage offering with Salesforce.com’s core CRM service and this week adding support for Salesforce.com’s Chatter social media services.

Box.net, which has yet to turn a profit, reportedly turned down a buyout offer of more than $500 million earlier this month. Salesforce.com brings a bigger, business-oriented audience accustomed to paying for online services. Chatter users can now bring their shared files and associated comments over into their Chatter stream.

That business user is a lure for Box.net. It just announced Box Sync for Windows and Box Sync for Mac both targeting these “information workers”  who want easy access to cloud storage and synchronization. These Box.net services will let those workers connect their desktop-based content to the cloud, incorporate that content into their workflow and access it from anywhere. And they will still be able to work offline in their applications of choice, the company said.

The company claims more than 100,000 users and has raised $100 million in venture capital since its founding in 2005.  Cloud storage is a hot area but also one that is hotly contested by an array of competitors including  Dropbox and Mozy, and others.

Box.net’s existing backers include Andreessen Horowitz, Draper Fisher Jurvetson, US Venture Partners and Scale Venture Partners, among others.

Additional reporting by Derrick Harris.

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