Senior Product Marketing Manager at Microsoft Ben Hunter recently blogged about a new way that Windows 8.1 can be installed while still ensuring that there is plenty of storage left for apps and data.
The method uses the well-known Windows Image Boot format. But instead of uncompressing the image during installation, WIMBoot keeps all of the operating system files compressed on a separate partition. From the user’s perspective, however, nothing looks any different: You still see a C: volume containing Windows, your apps, and all of your data.
A standard WIM file is not usually bigger than around 3GB. This allows for installation on devices with smaller disks, e.g. devices with 16GB or 32GB SSDs or eMMC storage, while still ensuring that there is plenty of storage left for apps and data.
Note that UEFI is a requirement and that WIMBoot will only be supported on Windows 8 logo-certified devices.
Read more about Windows Image File Boot (WIMBoot) here.
http://technet.microsoft.com/en-us/library/dn594399.aspx
Read about Michael Niehaus experiences from experimenting with WIMBoot using MDT 2013 here:
http://blogs.technet.com/b/mniehaus/archive/2014/04/13/experimenting-with-wimboot-using-mdt-2013.aspx