You have a few ways to do this. If you are doing a few migrations then the tool that Joe pointed out is good. If you're doing more and want to have more control, then you'd set up VMM to connect to your vCenter and do a V2V conversion. If you have 100+ VMs then there's a new package solution based on System Center 2012 that is based on automation, self-service, and governance: http://www.hyper-v.nu/archives/hvredevoort/2012/04/virtual-machine-migration-toolkit/
Dunno about others, but what i have seen is people moving from a single vmware host to multiple Hyper-V hosts. I haven't seen any large migrations from vmware to hyper-v.
Maybe that will change with hyper-v 3.
'People who think they know everything are a great annoyance to those of us who do. ' Quote by Isaac Asimov
We currently have 7 VMWare hosts that are running about 30 of so guest servers. We will be moving to HyperV this summer, ours is mostly due to cost and the fact that we never use all the bells and whistles of VMWare. We are a K-12 school division if that sheds any light on the pricing angle :-)
We moved as soon as Hyper-V was available, although at the time we were using the old VMware server so it was a big step up for us. Have been on Hyper-V since.
We are running side-by-side and maintaining our current VMWare licenses, but will not be purchasing anything additional.
Michael D'Angelo (former)MVP-MIIS, Pace University Senior Systems Administrator (Windows)(MS)NMDANGE PhoeniX WorX Systems Administrator. If you play Total Annihilation, please join us. http://www.phoenixworx.org