Can Parallels and VMware Fusion use the same boot camp volume? I'm planning on installing the trial versions of both Parallels and VMware Fusion to try them both out. I have a Boot Camp partition which I want to use instead of installing another OS. My question is if both of these applications can use the same Boot Camp partition without modifying it; such that both could be installed at the same time without it affecting the other.

Update: I installed the VMware Fusion trial version. In order to enable many of VMware Fusion's features, they require that you install VMware tools on the virtual machine. I'm not sure if its compatible with Parallels or if Parallels has its own software they recommend you install on the virtual machine as well.
Yes.  The virtual machine creates virtual machine files, the data on the volume is separate from that.