For those interested: I was able to install and run hamachi just fine via Windows XP pro under parallels. Connected to my (three) networks, able to peruse shares, etc. Unless and until a GUI-based version comes out for Mac, I think I actually prefer using my WinXP VM to having to 'sudo tuncfg' and then start, login, etc. etc. via the command line.
There is a GUI for OS X, FWIW. It's called "HamachiX" http://homepage.mac.com/lxr/homepage/spaceants/hamachix/
Yeah I realized that, but it's awkward and doesn't work on a lot of my non-Tiger machines. I still prefer command line until an official GUI comes out. Or the Win version in Parallels.
Follow up and FYI -- Hamachi via XP is still working great. However, if you need to install Hamachi via OS X as well, you will need the Universal version of the tun/tap driver. I thought there might be a problem with the Parallels TCP/IP driver and then found out that I had the wrong tun/tap driver.