The Linux SCSI Target Wiki
Vmware ESX v4.x has been tested with LIO-Target v3.x with virtual (IBLOCK, FILEIO) TCM storage objects. Using export of physical (pSCSI) TCM storage objects should work as well given that the underlying SCSI LLD supports SPC-2 RESERVE/RELEASE.
By default, ESX v4.x uses Thin Provisioning and will call SPC-2 RESERVE/RELEASE as new blocks are written to update it's VMFS metadata.
See the "Thin Provisioning" section on pages 116 through 118 in VMware's "ESX Configuration Guide", ESX 4.0, EN-000106-00, retrieved from vsp_40_esx_server_config.pdf
Note that Vmware ESX v3.x is currently not supported because it depends upon Task Management Function WARM_RESET.