First of all it seems that Grid computing has been on a general downward trend for 4 years.
- Four years ago Grid computing had a comparitive ranking of 100 vs cloud 0.
- Two years ago 33 vs 0.
- One year ago 26 vs 1.
October 2007 seems to have been tipping point.
- October 2007 the comparision was 25 vs 10
In April of 2008 Cloud computing surpases grid in search interest for the first time
- April 2008 the was 27 vs 28
The increase from April to July has been stagering.
- July 2008 - 21 vs 100
In less then two years cloud computing has managed to surpass the highest levels of interest in comparision to grid computing.
Take a look at http://www.google.com/insights/search/#cat=&q=grid%20computing%2Ccloud%20computing&geo=&date=&clp=&cmpt=q