Here's one that could be for the records.
I was speaking with Egenera's CTO last week, and he mentioned -- in passing, and without too much fanfare -- that a customer was experimenting with PAN Manager and VMware ESX to see how many guests a single BladeFrame blade could support.
In this case, the hardware was a single Egenera blade with 96GB of memory w/four 6-core Intel chips. The customer was able to load-up and run ~180 VMware guests, each with 512MB of memory. They then ran their own disk I/O tests (to generate I/O) with levels similar to applications they run in-house. In practice, they said, they found *180* to be an upper threshold, and that the more reasonable number that could operate without significant delay was *reduced* to 150. Yikes.
Similarly, on a 32GB blade, upper limit was ~50 VMs, with ~40 being a reasonable operational number.
Obviously, other customer mileage will vary, and this customer's tests weren't based on standard benchmarks. And, clearly with very large apps each with high I/O, this may not be a reasonable number. But it was with these folks.
Now here's an interesting follow-on thought experiment: PAN Manager + hardware is designed to manage up to 24 physical blades (or Dell servers) meaning it dynamically creates I/O, manages the network fabric, and makes appropriate storage connections (for either physical or virtual apps). Doing-the-math shows that it's not a pipe dream to consolidate a modest-sized data center into a single PAN-managed rack. Cool.