USB in Hyper-V Child?
It's still early days yet, but I think I've found a simple and very satisfactory solution to the problem of no USB support in Hyper-V. FabulaTech's USB Over Network product is simple to install - you install the Server side of it on whatever physical machine will host the USB devices, and the Client side on whatever virtual machine needs access to the USB devices. You can install as many copies of the Client application as you want - it's only the Server that requires a license key.
Fabula claims to support 64-bit, and it does run in Windows Server 2008 x64 version. BUT. And it's a big but. Unsigned drivers! I've already got a message in to them to find out what they're going to do about this, but in the mean time, it's a useful solution to test out, but isn't going on any production machines until they get that fixed.
Using the product is simple - install the server, start it up, configure the port (and set an exception in Windows Firewall).
Then, simply plug in a USB device to physical computer. USB over Network recognizes the device, and makes it available to clients.
On the client side, install the software, start it, configure for the same port and point to a server by name or IP address, configure Windows Firewall. Now, browse the list of USB devices on the server. Connect to the one you want, and it's recognized exactly as if it were local to the client computer. Even if it's a VM with no USB support!
So far, it works a champ for using a USB hard drive as my backup device in SBS 2008. Which is exactly what I wanted it for.
More when I've had it up and running a few days, and when I've heard back from FabulaTech about signed drivers.