The big IT vendors aren't taking social software seriously. They can't. Not even if they wanted to. They're wedded to a massive install base and business model based on extremely profitable file-based applications. There's no easy way out. This very thing happened ten years ago to the photography market. That's why the ten-year stock prices below could very well be a glimpse into their future. Sounds extreme but I imagine the same was true in the late 90s when folks said that digital photography could upturn everything.
Once upon a film
Kodak had a monopoly on the film business for decades. But at the end of the 1990s, consumers finally got the chance to use something they loved: Pain-free (digital) photography. It made photography accessible, fun, and immediate. No more trips to the store for film. No more waiting to see if you got the shot. No more expensive processing and film. This huge demand made it's way into commercial business as well. Sound familiar?
No longer relevant
Kodak dominated the imaging market for decades but their entire DNA was about film. I happen to know first hand that the company didn't take digital seriously for a long, long time. In 2003, I had meetings with film and digital people. All of us would be in the same room and the digital people were always shoo-ed like buzzing flies. That's even after their CEO had vowed they'd become a leader in the digital space (late in the game). I'll spare you the details of those meetings but suffice it to say, back then it was obvious they didn't have the people or culture to stop the digital strangling.
Radical change needed 
I'm not trying to say Microsoft will go the way of Kodak (or even Polaroid). I mean, IBM is still around and they used to rule the PC roost. Transformations happen. Apple did it. Dell's trying to. But typically this sort of transformation is rare, expensive and born from innovation. Not something Redmond is known for. Making fundamental change requires companies to overhaul everything they do-from planning to manufacturing to marketing. It's something Microsoft will have to do to enter into the consumer advertising market, let alone deal with their massive document dumps vs the people-centric social software movement.
The next enterprise software leaders
Canon used to be fax machines, printers and copiers. They were able to reinvent and capitalize on the digital imaging market and flip flop leadership with Kodak. Kodak is still a player but now there's a wholly new set of competitors. The same thing will happen for enterprise software. Sure Microsoft, IBM, SAP, and Oracle will be around but there will be room, for the first time in decades, for new players to capitalize on the massive demand and emerge as leaders in a wholly shifted playing field.
