You can hear the man himself talk about the rebuilding project here:

http://www.cbc.ca/spark/2011/10/full-interview-john-graham-c...

Just to be clear, Difference Engine no. 2 was completed in 2 parts: in 1991 and 2000. However work on the _Analytical Engine_ has just begun in the planning phase, and excitingly it will be a crowdsourced endeavor.