In case you missed the announcement last week at the Microsoft Management Summit in Las Vegas, the beta for VMM VNext (now called VMM 2008) is publicly available - you can download the software here: http://www.microsoft.com/systemcenter/scvmm/default.mspx
The beta is nearly feature complete meaning that in one form or another, we have implemented all of the new functionality including Hyper-V support and VMware support. Of course, good ol' Virtual Server is still fully supported as well. It is of course a beta so it's still a little rough around the edges so you can expect the final version to have better overall performance, reliability and scale but the beta should get you pretty good mileage in the mean time. I was able to demo VMM 2008 in front of 4000 IT Professionals last week and was interrupted several times for spontaneous applause. Assuming that wasn't just our team, people liked what they saw :-)
While the beta has nearly all of the features baked in, there are a few things that we're still working on for the final release later this year so stay tuned and I'll run some of them by you in future posts. Until then, download the beta and don't be shy, give us honest and direct feedback.