On the ad-supported side, offerings such as Google Apps and Spiceworks' IT management software are gaining momentum. Spiceworks, which offers its software for free in exchange for displaying ads in a portion of the management console, says its ad revenue has grown 900% in the past year (though the company declined to say how much money that actually translates into). It also says its doubled the number of its users, to 200,000.
For years consumers have been willing to endure advertising in exchange for software and services. Spiceworks is proving that many businesses are also comfortable with it. Spiceworks targets small companies (up to 250 employees) that have small IT staff and cash-strapped budgets.
Of course, ad-supported enterprise software is still in its infancy. It's hard to envision large enterprises embracing this model, particularly when, as in the free version of Google Apps, ads are generated based on user content. This presents significant privacy challenges to large (and regulated) businesses.