Here’s a brief according to Irina herself:
While working for Google I created this little green dude as part of the launch campaign. The idea was to create the open source logo (very much like open source Android platform), that was released to the developer community without regular brand guidelines. Not unlike Linux Penguin, the logo helped to establish identity for the new product and generated excitement among engineers. Initially the logo was meant for developer community, but it quickly became consumer facing with millions of people creating their own versions of the logo every day.
It seems the Android logo is another logo that will, if not yet, achieve worldwide recognition despite of its quite humble beginnings. Can you name another one?