Sun's acquisition of the VirtualBox project is very much part and parcel of what is probably Sun's single greatest thrust--to reconnect with the development community that it once essentially owned but who abandoned it en masse for Linux.
As with other companies serious about being viewed as virtualization players, Sun has found that one size cannot be made to fit all. Thus, Sun's early religion around the operating system containers built into Solaris 10 has given way to more of a toolbox approach that most notably also includes its Xen-based xVM Server.
Thus, Sun's most recent addition--the Open Source VirtualBox (by way of acquiring Innotek) isn't particularly surprising. But it makes a nice addition all the same.
VirtualBox is a "Type 2" hypervisor product, which is to say that it runs on top of an existing operating system rather than directly on top of the underlying hardware as does a native hypervisor. Thus, from a technical perspective, it has similarities to VMware Server and Microsoft's Virtual Server, which are also hosted virtualization products. The disadvantage of this approach is that there's more overhead involved--especially for I/O-intensive workloads. However, in exchange for this overhead, the hypervisor gets to piggyback on all the device drivers and other interfaces already built into the OS. Hosted virtualization products can thereby support whatever peripherals and I/O cards are supported by the native operating system right out of the box.
Some other facts and figures about VirtualBox and Innotek:
This acquisition is a positive move for Sun. One thing that Sun's virtualization portfolio was missing was a true developer on-ramp that offers a no-cost mechanism to "play around" with (specially) Solaris on an existing laptop or workstation. Like the MySQL acquisition and aspects of "Project Indiana," this is all about providing easy entry path into the Sun ecosystem that developers want to head down.
Based on our very preliminary tire-kicking, the product still needs some work. For example, when my colleague Jonathan Eunice tried to load a VMDK (VMware VM disk image) for the latest Solaris Express Developer Edition (SXDE) using VirtualBox, the VM just endlessly rebooted. Senior Sun technical people took a close look at VirtualBox before the acquisition and liked what they saw. I've also started to hear positive buzz online about VirtualBox of late. So I have little doubt that Sun get get VirtualBox up to full snuff. But it will take some development.
It's a different approach from VMware. In VMware's case, it's their original server product (VMware Server, nee GSX Server) that's free; VMware Workstation still carries a charge. To be sure, in practice, lots of people try out VMware on their desktops using VMware Server. Nonetheless, we see here a difference in philosophy. Sun, especially CEO Jonathan Schwartz, has had a mantra over the past couple of years about how "developers don't buy things; they join things." In fact, the roots of this thinking at Sun go back almost a decade; Sun Open Sourced Netbeans in 2000--before Eclipse came on the scene.
VirtualBox also provides an on-ramp for other Sun properties. When Sun pre-briefed us on this announcement, they made considerable ado about using pre-packaged virtual appliances to get developers up and running quickly with products like GlassFish, the Open Source application server that Sun is backing. Virtual appliances are a promising idea--although in practice they've been laggardly. If Sun truly wants to leverage the appliance idea here, it will have to get aggressive in kickstarting a library of up-to-date instances.
In short, this is very much part and parcel of what is probably Sun's single greatest thrust--to reconnect with the development community that it once essentially owned but who abandoned it en masse for Linux. VirtualBox isn't a heavy gun in this effort like MySQL is. But it's a nice little bodkin.