i did a bit of snooping around on this and this is what i could dig up, about the only demo that is trackable is geoip so we can get a glimpse of where thing are happening, this is all data on the blockchain though, not just mining. i also thought a map of bitcoin meetup group might be of value:::::::
map of bitcoin meetup groups
http://bitcoin.meetup.com/
the is a chart of country of host IPs, it shows a geo distribution of p2p clients on the blockchain over time.
Country Number of Hosts
United States 6458
Germany 1113
Russian Federation 941
Canada 855
United Kingdom 827
Australia 529
Netherlands 344
Poland 335
Ukraine 316
China 304
Sweden 271
France 263
European Union 252
Finland 243
Italy 179
Czech Republic 167
Spain 161
Brazil 147
Switzerland 122
hope that helps!