MacBookPro G5 Blackberry through VZW
I have successfully tethered via USB by using Parallels. It works, therefore, on my Windows XP side.
I have yet to try it with Mac applications (e-mail and Mac browsers) which are available at the same time. Since I have wifi in my home, I want to wait until out of the house to avoid any overlapping coverage. I'll report back after testing.
BTW, VZW does not charge anything extra for the service as it is included in the basic Blackberry package.