Hyper-V monitoring is available since NPM 10.4. Set up instruction you can find in SAM admin guide - http://www.solarwinds.com/documentation/apm/docs/SAMAdminGuide.pdf in a chapter "Hyper-V Monitoring".
Thanks for the heads-up! Somehow, someone in our organization changed all of our Windows servers from WMI monitoring to SNMP monitoring. After looking at the SAM admin guide, I checked a short selection of systems and discovered they had all been changed, which explains why the Hyper-V info was missing.
That is getting fixed ASAP!