Wow, I have never come across that. Almost universally the customers I talk to are loathe to change the hypervisor because they have it working across so many different platforms that they don't want to qual version 4.0 across all of those platforms.
When they launched, Nehalem there were a few benchmarks that showed negative performance for SMT. Just like the good old days with SQL Server and hyperthreading.
And we also support it in VMware ESX 3.5. I believe intel only supports it with VMware 4.0 (VSphere). Upgrading the hypervisor is not on the radar for a lot of customers.
Actually, when we laid out the project, we planned for a major spin and some minor tweaks before we would have production silicon. The first silicon came out strong enough that our partners said "let's take it to market." No corners were cut. When you start with the solid Shanghai silicon it makes it a lot easier.