The Industrial Cluster Project of Japan published its 2008 annual report this month. Visit the (expired link).
The report contains interesting statistics on sales, profits and employment in small and medium enterprises (with capital less than $11M) who participate in Japanese cluster initiatives.
For example, in the 2000-2007 period sales increased by 28.1% (compared to just 3% in all of Japan), profits by 113% (compared to 27.6%), and employment by 1.8% (compared to a 5.4% decrease).
More at the site of (expired link).