The United States Patent and Trademark Office has admitted a patent for Modular Data Centers housed in shipping containers, which Google curiously notes facilitate 'rapid and easy relocation to another site depending on changing economic factors'.

The application was filed in Dec 2003 already(!).

Link:
http://patft.uspto.gov/netacgi/nph-Parser?patentnumber=7,278,273

via YRO section of /. http://yro.slashdot.org/article.pl?sid=07/10/09/1543256

Interesting that they patented the idea but don't seem to be using the idea themselves.

I've heard about IBM doing something similar to this, anyone has any idea?

This has been discussed here before, but I believe I read somewhere that Google againsted the idea.

There is more on this at slashdot.
http://yro.slashdot.org/article.pl?sid=07/10/09/1543256

In 2005 Cringley mentioned:

"The Internet Archive sponsored presentations trying to drum up interest in this concept (the presentation, itself, courtesy of Bruce Baumgart, one of its authors, is one of this week's links) and at one meeting Google's Larry Page was in the audience. I guess he must have found something of interest."

http://www.pbs.org/cringely/pulpit/2005/pulpit_20051124_000474.html

The slashdot report gives more references and says this predates Google's patent application.