This concept of Bootlegging[1], isn't "Google's" and dates back to the late 1960s. I always think of Post-it notes as the pre-digital poster child for this sort of internal, yet personal, innovation.
Bootlegging is an unnatural term, and has a historically negative connotation. The definition mentions secrecy and unauthorized projects, yet a few paragraphs later awkwardly adds a permitted form.
The official definition from Knight's seminal paper "A Descriptive Model of the Intra-Firm Innovation Process" [1]:
"Bootlegging: In some instances the innovator may be able
to implement a new idea by keeping the development under
cover from the disapproving power in the organization
until it is introduced. At that time it may be impossible
for the organization to reverse itself."
It's reasonable to consider the authority of a Wikipedia entry, but in this case I believe the maintainers simply modernized "under cover" and "disapproving power".
[1] - http://en.wikipedia.org/wiki/Bootlegging_(business)