In comp.os.linux.misc Tim Watts wrote:
It would be fun to sniff the conversation between Drive and my
- computer with a minimal client so I don't see all the web
- supporting stuff.

I *wonder* if it is something that could be reverse engineered into a
home server...

Another one that has not come up yet (at least that I recall):

Tahoe-LAFS https://www.tahoe-lafs.org/trac/tahoe-lafs