Sharepoint is open source's biggest threat, according to Brian Behlendorf. I concur. But what many enterprise software companies fail to recognize is that Sharepoint is going to be their biggest threat, as well, as Sharepoint corrals content and applications into the Microsoft ecosystem.
IBM, however, is no dummy. It is ramping up a response to the Sharepoint threat, as CMSwatch discusses:
The sheer number of tools and technology announcements coming out show IBM has gotten the message that Web 2.0 is a critical component of business applications these days. Do you think they have a chance of winning over the volumes of companies and users of Microsoft collaboration technologies? SharePoint is so deeply embedded in many organizations today.
What IBM hasn't figured out is how to virally distribute its Lotus and other collaboration tools, as Microsoft (and open-source vendors like Alfresco, my employer, have). It's one thing to come up with great technology. It's quite another to get it in the hands of prospective customers. IBM doesn't have a good story there that I can see.