Currently, WUBI allows the installation of Ubuntu alongside/inside Windows without re-partitioning the hard drive. It does this by creating disk images of each of Ubuntu's partitions and mounting them instead of a physical disk partition.
Therefore, it should be possible to mount these disk images in a virtual machine and run Ubuntu directly inside Windows. However, WUBI does not include or install any software to be able do this, which would be especially useful for users who are not confident with computers or operating system virtualization.
While the importance of this feature may be debatable, it would be invaluable for those who constantly find themselves switching back and forth between the two operating systems for different uses.
Furthermore, adding this functionality to the WUBI installer may prove to be a valuable asset in Ubuntu's future, as more users may be willing to install and use Ubuntu inside Windows than boot it independently. This is especially true if there is a sizable user base that has the need to run Ubuntu and Windows applications simultaneously without much headache.
