On the surface SharePoint is merely a document management system which lets everyone in your company share and find Office documents easily. But critics like our own Matt Asay call it a Trojan Horse, which will bind companies which deploy it to Microsoft forever.
You can put together everything SharePoint does using open source projects, but it takes work. You can combine Alfresco (from the Electronic Content Management (ECM) software company Matt works for), the Liferay portal, JasperSoft for reporting, and Zimbra’s e-mail server. Throw in some Jive forums and you’re more than done.
But what does that cost, really, compared to just using something from Microsoft which already works with your current Office applications? Exactly.
Once companies start using SharePoint, Asay worries, there is no way for them to ever ditch Microsoft applications and file formats. SharePoint is tied to those formats, and as the share fills the cost of switching away rises exponentially.