I already mentioned the Open Source VirtualBox in an earlier blog item. But, that version was only available for Linux and Microsoft Windows. As of April 23, the Mac OS X version became available. It is a virtualization product that lets you run multiple Guest Operating Systems (say Windows or Linux) at the same time that the host (main) OS is running on a single computer. Parallels Desktop for Mac was previously the only production virtualization product available for Mac OS X (VMware Fusion is still in beta). Virtual Box gives Mac OS X users a free Open Source virtualization engine to try.