The main problem with corporate social software today is that the business dynamics are different than public social apps. With Facebook or Google+, you are a user, not a customer, and advertising is the business model. With corporations, you buy, not build the software and typically it is bloatware, trying to meet the needs of a selection committee with vague goals. So, if you can find anything good, it will be expensive (SAP, Microsoft, Oracle, etc).
Digital Equipment Corporation (DEC) had a vibrant social network from the mid-80's to the mid 90's, based on a rewrite of the CDC Plato software. It eventually evolved into Lotus Notes and bloated into crapware. In it's day at DEC, over 400 "notes files" were active, half business related - and non-business topics to encourage use by everyone. Below the management level, the company ran on "VAXnotes". Management hated it, because it wasn't the way they were comfortable working and disrupted their authority. Did this kill the company? Perhaps. It sharpened the disconnect between management and the workers.
Today, combine bloatware social tools that basically suck when compared to public sites, with corporate rules that discourage non-business use, combined with the spyware culture that social tool reporting provide - and we see failures due to non-use. Once those that grew up with social tools grow into management positions, the popularity of corporate social tools will likely grow. Use of social business tools "CAN" be a powerful tool if the corporate culture embraces it. It "WILL" make companies more competitive if the culture can act in a more coordinated way. Just, not yet.