A client of mine wanted to know if OBIEE will scale for upto 400 users and I sent him the following link. The link is an introduction by New York City Mayor Bloomberg to CPR 'Citywide Performance Reporting Tool' followed by a demo. The tool is targeted for all city residents to see and report data from from than 40 city agencies.
So, from our perspective, this proves that OBIEE not only can scale, but it can source data from upto and more than 40 back-end systems.
http://www.nyc.gov/html/ops/cpr/html/home/home.shtml
The Mayor said “Welcome to the next generation of data reporting for New York City. CPR will help YOU the public can monitor the performance of city agencies. … the tool make information available to the public, and making government as transparency as possible."