There's a new Corillian/Microsoft Scalability Case Study. A few highlights (Emphasis mine):

• Currently, more than 19 million end users—or about 25 percent of U.S. online banking customers—use Corillian technology when they use their institution's online services for transactions such as checking balances, paying bills, and transferring funds between accounts. (Not bad for a Microsoft-based platform, eh? .NET works.)
• Voyager 3.1 was able to support 70,000 concurrent users across multiple lines of business.
• Voyager 3.1 was able to support a sustained throughput rate of more than 1,268 transactions per second — about 4.5 million successful transactions per hour—and a sustained session creation rate of more than 208 new sessions per second.
• Voyager 3.1 supported more than 129,000 concurrent sessions across the system at peak load. This includes both active sessions, in which a user is executing transactions, and inactive sessions.
• Voyager 3.1 supported a ramp-up from 0 to 70,000 users in only 15 minutes—without any adverse impact on performance—demonstrating that Voyager can sustain a large burst of users accessing information in a short time period without overwhelming the system.
• Voyager 3.1 surpassed its previous benchmark of 30,000 concurrent users by 133 percent, with only a 32-percent increase in overall hardware cost.

It's fun to work on big stuff at Corillian. The case study is at the Microsoft site here.