Don Park thinks that a competitor smart enough to leverage the open source community should be able to run circles around Documentum. But things aren’t quite what they seem. If you take a look at Documentum’s Financials, you’ll see a bit over half of their operating cost goes to sales and marketing. And that sales and marketing costs are 2-3 × R&D costs.
Document/Content Management is still a market in flux. Documentum Sales and Marketing is spending a lot of that money to define the market. An open source alternative probably can’t afford to compete until the market is defined. Of course, open source could go after a different market segment and grow to compete with Documentum a few years from now.