In ESX(i) you will find deduplication in two places.
"Transparent memory page sharing" uses deduplication to optimize physical memory usage.
However, I think what you are asking for is deduplication on disk. This is only used by VDR "VMware Data Recovery" to save space on the backup destination. Deduplication in VDR is enabled by default and is done online (software based) so there's no need for special hardware.
André