After a while of struggling, I have to admit that SharePoint is going to take the lead in Enterprise 2.0 world. The challenges are not just about having a good collaboration platform, but a platform that integrates email, IM, calendar&schedule, and, most important of all, business intelligence. By the way, I would expect something more promising when Windows Mobile is tightly integrated with SharePoint.... The future enterprises will go mobile and MS is definitely the closest one to provide a fully-integrated solution.
On that sense, Google is the runner-up in the game at this moment. I believe that Google will take on the Cloud-computing as its main architecture. The mind-set or belief of enterprise users will basically set the business future for Google in this market. And I am not quite optimistic for this. Only SMEs and private users have the courage to take on the challenges. An incident such as information leakage can basically kill the belief of cloud computing technology in the market.
Where is IBM? Well, let's cross our fingers and see when Lotus Notes'time is completely over. I do believe that IBM is not able to take on the game if they do not have a serious re-consideration of their extensive use of java.
Any one else in the game? Well, we constantly see so many different tool-sets coming up (especially in the BI world :) that brings forward an organization in certain perspective. But everyone will soon find out that the cost of maintaining these different tools and their integrations will basically makes up their mind to migrate to a "single platform" strategy.
