Hello!
I bought one of the new MacMinis, which were presented yesteraday, plugged two 8GiB DD3-1600 modules in (OsX reported 16GiB of memory, as the models before) and tried to install ESXi 5.1 Build 799733. It started promising:
Initializing chipset...
Initializing timing...
Initializing scheduler...
Initializing processors...
Initializing ACPI...
*BANG*
Pink screen! 
NOT_REACHED bora/vmkernel/hardware/intel/vtd.c:3638
cr0=0x8001003d cr2=0x0 cr3=0x449ad500 cr4=0x12c
*PCPU0:4096/bootstrap
PCPU 0: SISISISISISISIS
Code start: 0x41800c600000 VMK uptime: 0:00:00:04.301
and a stackdump.
I tried instalkling 5.0 and 5.0 U1 also, but with the same result.
It is the regular MacMini with an i7 4C 2.3GHz and one 1TB SATA drive (http://store.apple.com/us/configure/MD388LL/A with no extras), not the MacMini Server.
Any suggestions? Thanks!
PS1: I was unable to boot the ESXi setup from USB key! Since other USB keys (OsX setup for example) didn't work either, I suspect that there's some EFI boot problem from the new USB3 ports. Booting from CD worked, however.
PS2: on the earlies models we had the problem, that the Alt key wasn't recognized after powering on, when there is an USB hub between the keyboard and the Mac (a KVM switch for example). That seems to be fixed now: whenever I press the Alt key at the powerup chime, I get the Apple "boot menu", even with our KVM switch in between.
@sirozha1:
Most questions are already answered in this thread. Just look back some pages.
USB3 obviously has issues on the new Mac. 3 out of 5 USB3 keys we tried are not recognized on the "Alt" UEFI boot menu. One even completely hangs the Mac, after it's inserted. All the USB3 Keys, however, ARE working, when OsX is running. So I expect some UEFI update soon.
USB3 as boot medium for ESXi won't give you the edge. If you choose some quick USB2 key, ESXi will boot up in 10-20 seconds. USB3 probably won't change that too much. Besides, how often DO you (re)boot ESXi hosts? 
I'm not a pro on the Mac. But with the prevoius MacMini Server we had problems, when ESXi was installed on the other drive and not on that one, which booted OsX. We found no way to change the boot device later [except manualle every boot with the "Alt" key]. So you might have a basic problem to boot from USB without manual intervention on each boot. Why don't you install ESXi on the internal drive? Every MacMini has one (or two). Simply use it. It gives you the same non-redundant solution, like booting from an USB key (which can accidentally be unplugged and has less performance).
Regadring the "Thunderbolt Drobo", you mentioned: I looked at their website. I found no information, how the RAID is being controlled. If it would be any kind of software RAID (like WD "My Book Thunderbold Duo" for example), you can foget it on ESXi. If there is a hardware RAID controller working in it, hat I believe to be the case, you have to find out, which one and if it's on the VMware whitelist. If it is, it will work. Thunderbolt makes a transparent PCIe bridge.
When connection multiple Thunderbolt devices to the MacMini, keep in mind, that it has just ONE Thunderbold connector and devices like the Apple Gigabit Adapter have no chaining output.
I guess the only real RAID enabled solution for the datastore for me is my ReadyNAS Pro 6 used as the iSCSI target for my current ESXi server (Dell PowerEdge), which I will have to re-use for the ESXi server running on the 2012 Mac Mini.
In most cases, SAN/NAS is to be preferred. DAS is usually only used in small applications, where you need "one box for everything". If you already have some SAN/NAS, be happy and use it for both machines.
Buy the US$ 29,- Apple Thunderbolt GbE for a redundant uplink.
does ESXi support the Wi-Fi Ethernet controller in the 2012 Mac Mini?
No.
afaik, ESXi does not support any WiFi.
Lastly, how would the performance of the 2012 Mac Mini with 2.6 GHz i7 quad core and 16 GB of RAM compare to my 2010 Dell PowerEdge with one Xeon 2.4 GHz e5620 CPU and 16 GB of RAM?
I cannot give you a precise answer to that, off course, but since the Dell is 2 years old and the MacMini has newest 22nm technology and 1600MHz DDR3, it should perform slightly better, than the Dell. All the ESX hosts we resp. our customers use (70+) suffer from lack of RAM and not lack of CPU power.
I've tried installing via SuperDrive on the new 2012 Mac Mini server using the standard 4 GB (two 2GB) of 1600MHz DDR3 memory and I can't even get started. I received a purple screen upon install that complained "No usable memory below 4GB"
Has anyone else hit this wall? I'm going to try third party RAM from Corsair later.
@HPReg:
I was able to get hand on another MacMini6,2 Late 2012.
1) Install Mac OS 10.7.x or 10.8.x as a host (instead of ESXi) on the Macmini6,2.2) Install VMware Fusion 5.0.1 (trial version if needed).
3) Copy or create a Mac OS VM, and try to boot it.
Do you see the same issue or not? Depending on your answer, we will know much more precisely which part of our code is causing the issue.
Installing OsX 10.8.2 in VMware Fusion on the new MacMini worked without any problem.
So the problem occours only with ESXi (5.1) on the new MacMini.
What now?