Hard to say. Historically you've only been able to move to the same version or newer. Vegas Pro 8 will open Vegas Movie Studio 8, 7, 6, and earlier files. I don't know if it will open version 9 files or not. There's a good chance that it won't. You may have to wait for Vegas Pro 9 to be able to open VMS 9 files.
However, i could be wrong since the Studio version always seems to be released many months before the Pro version. If a VMS9 user wants to email me a tiny .vf file i'll let you know if it opens in Pro 8 or not.
I am sorry to hear that. At least for simpler projects it works. I just tried it. I created some VMSP9.0b projects and I opened them just fine on Vegas Pro 8.0c.
What about the trusty Copy/Paste method where you select and copy the events in the timeline. I know it works between 2 open instances of Platinum. It might work between Platinum and Pro.