You know, with the much-ballyhooed push for ARM to enter server space, you'd think SMT would be highly-desirable. I don't think I've seen it on any of the server ARM chips put forth by the ARMy on paper or in silicon.
Broadcom's upcoming Vulcan ARMv8 CPU has four hardware threads per core. http://www.broadcom.com/press/release.php?id=s797235