Matt - all data comes from VC. There is no specific handling on temp vs any other metric.
Hence the suspicion expressed by the other folks in this thread is that VC does not send out correct data, value is not chaning, or something of the sort.
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I confirm similar behavior in my lab env though. Will try to find out more in the next few days.
Question: are you using the HP-customised installation for ESX or the generic one?
Update: check this KB http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1037330
If you want to play with it, it's worth implementing a PowerCLI script that does the outlined refresh/reset every xxx minutes, and see whether that affects the values displayed in vc ops 