I was reading about how XenSource (http://www.xensource.com/) recently closed their Series A round of VC funding to develop open source virtualization software. With almost every layer of the stack being virtualized, this is not necessarily a surprising announcement. However, what is interesting is the speed with which profitable sectors of software seem to be getting open sourced. It took awhile for Linux to get out of the blocks and target the operating system in a meaningful way. It took less time for JBoss and MySQL to start getting traction. All three of those companies decided to take part in niches of the software stack where one could argue that the products were maturing to some degree. However, the interesting thing about the XenSource is that virtualization is still in its early days, particularly if you are talking about server virtualization. By all public accounts, VMWare has been a great growth engine for EMC and this is a product category that is still in hypergrowth mode.