ESXi 5.1 Update 1 was just released by VMware and similar to the ESXi 5.0 Update 2 release last year, the tg3 (Broadcom) driver has now been updated to 3.123b.v50.1 which is required to support network connectivity on the Apple Mac Mini's. Prior to this, to install ESXi on an Apple Mac Mini, users were required to build a custom ISO that included the updated tg3 driver and I am happy to say this is no long necessary! In addition, having the latest driver also provides out of the box support for the Thunderbolt ethernet adapter which is great if you are looking to add an additional ethernet connection to the Apple Mac Mini.
Apple Mac Mini 6,2 Users
If you have an Apple Mac Mini 6,2 the workarounds described in this article are still required as well as an additional issue regarding the on-board NIC for the Apple Mac Mini 6,2. The issue is that the on-board NIC is not recognized and claimed by the tg3 driver because there is not a PCI ID entry in the tg3 map file. Note, BCM57766 driver is supported, just that it was missing the mapping (I believe this was the case in 5.0 as well). Working with VMware engineering, I was able to obtain the SMC fix and along with the workarounds that I built earlier for ESXi 5.0 and I have created a custom ESXi 5.1 Update 1 ISO that includes all the fixes and you will be able to install it on your Apple Mac Mini 6,2 without any further modifications.
UPDATE: When trying to enable vSphere HA, the following error "Could not find a trusted signer" is thrown. To get around this problem, you will need to manually install the vSphere HA VIB and then reconfigure vSphere HA. The easiest method is to SCP the VIB from the VCSA and then using ESXCLI and the --no-sig-check flag to install the VIB.
Here are the commands to run:
scp /etc/vmware-vpx/docRoot/vSphere-HA-depot/vib20/vmware-fdm/VMware_bootbank_vmware-fdm_5.1.0-1064983.vib email@example.com:/tmp
esxcli software vib install -v /tmp/VMware_bootbank_vmware-fdm_5.1.0-1064983.vib --no-sig-check