Today the news dropped that San Francisco-based SaaS Web content management vendor, Clickability, which had previous raised more than US$ 15 million in backing, was purchased by Limelight Networks for US$ 10 million. Ouch.

Limelight’s aim with Clickability is to compliment its video platform business, a market the company entered last August when it purchased Delve Networks. The company says Clickability will add between US$ 4.5 and 5 million to its total sales during the second half of the year.

“Clickability is a perfect complement to our Limelight Video Platform business, where we are seeing strong traction and where revenue has doubled since we acquired it six months ago,” explained Jeff Lunsford, chairman and CEO of Limelight. “Traditional IT services and software applications are migrating into the cloud for better scale, higher performance, and global reach. With the addition of web content management, Limelight can now help customers capitalize on this important trend by handling the complete website lifecycle in the cloud, including publishing workflow, website hosting, site acceleration, video publishing, mobile and tablet distribution, and effective monetization utilizing closed-loop marketing.”

All well and good for Limelight Networks, but what about Clickability’s investors? A US$ 5 million dollar hit sounds pretty bad.

Further, it touches on an interesting prediction made last year by Tom Wentworth, CMO at Ektron:

Web CMS acquisition fever will slow down, or maybe even stop.

The last five years have seen transformative acquisitions in the Web CMS vendor landscape. Oracle bought Stellent. Open Text acquired RedDot. Autonomy purchased Interwoven. Open Text bought Vignette. And most recently, Adobe acquired Day Software. In 2011, the acquisition fever will slow down as the remaining best-of-breed vendors focus on growth and differentiation in the next wave of Web CMS.