The feature allows Windows 8 to boot from a USB device. First discovered in leaked builds, Microsoft looks set to detail the future fully in a BUILD session this week:

“Windows To Go is a new feature in Windows 8 that enables enterprise administrators to create USB drives containing complete, managed Windows images that users can use to boot and run Windows on any Windows 7 or Windows 8 capable computer. Windows To Go makes it possible for employees to use a managed device whether they work from home, a client office or in a free seating environment. This session will discuss Windows To Go, its hardware requirements and building compatible and complementary software.”

Windows To Go: Run Windows 8 from a USB device | WinRumors

Anyone have there 16GB USB stick ready?

A well known SF member has a Windows 7 portable version that fits easily on a 4GB USB stick.

No ,there is no Portable Workspace Creator in this version. In previous, leaked versions it was in System32 ,but it does not exits here.