I recently upgraded my MacBook Pro and Mac Pro to OS X Lion, and I've only come across two minor issues.
Cannot open the disk '/Users/AaronBertrand/Library/Application Support/VMware Fusion/Virtual Machines/Boot Camp/Boot Camp.vmwarevm/Boot Camp.vmdk' or one of the snapshot disks it depends on.
Reason: The partition table on the physical disk has changed since the disk was created. Remove the physical disk from the virtual machine, then add it again.
I verified that I could boot to the Windows partition on bare metal, and that the virtual machine was intact and running as expected. It also took me a few minutes to find the vmdk file and verify its location, since all Library paths are hidden by default in Lion. To unhide them, open a Terminal window and run:
chflags nohidden ~/Library/
So I booted back into OS X Lion and followed these steps:
Now, when you start up your VM for the first time, VMWare will have to re-initialize the VM, so it will take a few minutes. I suspect this just changes a bunch of bits to the same bits, since the VM should already be optimized to run under Fusion (you'll notice it doesn't go through the VMWare Tools install like it does when you first create a VM or initialize a Boot Camp partition for VMWare).
You might also find performance a bit sluggish once you're up and running again – this is because VMWare set the CPU and RAM back to their defaults (1 core, 1GB). You will also notice that if you had set a custom CD/DVD drive prior to the OS X Lion upgrade, this is back to the default as well – and you may have to update other custom settings such as shared folders, sound, what have you. Shut down the VM, adjust the settings, and then you should be all set.
Hope this is useful to some of my fellow Mac converts. 🙂