citrix
I suppose you could also mention that Citrix uses FreeBSD for their Netscaler load balancer platform (of which they have virtual appliances named VPX).
Though it looks like VPX has been supported on Hyper-V for a couple of years now ?
http://www.citrix.com/English/ne/news/news.asp?newsID=2300624
If that's the case it implies FreeBSD has worked fine for a while, wonder what the new code was about - perhaps performance related or something, maybe native drivers for Hyper-V.