Today's Building Windows 8 blog post is from Rajeev Nagar, and describes how Windows 8 can natively mount and work with files stored in ISO and VHD files.

For those of you who don't know, ISO files are images of CDs or DVDs that can be stored on your hard drive and burned to a disc - many install disks, including Windows and most Linux distros, come in ISO format when they're downloaded. Windows 7 introduced the ability to burn ISO files natively, but you still have to download a third-party program to actually mount them without burning them to a CD. ISO mounting in Windows 8 replaces those third-party programs with similar functionality - Windows will assign a drive letter to a virtual optical drive, at which point you can browse the ISO and do what you need to with the files, and the unmount it when you're done.

Virtual Hard Disk (VHD) files are similar to ISOs, except that they store the contents of an entire hard drive. Virtual machines created using programs like Virtual PC, VMWare, and VirtualBox use (or can use) VHD files to store an entire bootable OS without the need of a physical disk. Working with VHD files in Windows 8 is a lot like working with ISOs - they're assigned a drive letter and then treated as a physical hard drive by the OS, allowing for viewing, adding, or modifying of files.

None of this is ground-breaking technology, but I like to keep my OSes as clean as possible, and I always appreciate it when new Windows features obviate the need for third-party plugins.

Source: Building Windows 8 Blog