MindTouch bills itself as the open source alternative to Sharepoint and recently named our own Matt Asay as the second most-influential executive in open source. (You're number one in my book, Matt.)
Pricing starts at $7/month, but you can try it free. It allows non-programmers to overlay data from a variety of internal and external resources in a single collaborative environment.
You might consider it an enterprise mashup service akin to Salesforce.com's Chatter. But while Chatter is focused on social media MindTouch is focused on enterprise data -- Chatter is about social and MindTouch about media.
Of course that last may be a comparison of sales pitches, not feature sets. MindTouch is launching its cloud just a week after announcing its Enterprise Dashboard, so these features may just be at the top of its mind right now.
Clouds will bear careful watching in 2010. They not only abstract complexity and virtualize everything, but they also blur the lines of open source and proprietary with a unitary business model based on SaaS. Which means everyone in software competes with everyone, and on the same playing field.
Which would leave me with nothing to write about. Maybe I can finally start that novel.