Lurker here. Picked up my optimus v a couple of days ago from Target. Also interested in rooting.
z4root installs just fine, but both the temporary and permanent root options do not work for me. The phone just stays at the "running exploit screen" forever. Other have reported that z4root runs to completion, but upon rebooting they still don't have root. I never see an error message in my case.
I also tried uploading busybox, su, and rageagainstthecage manually and rooting that way. Everything executes ok, the adb sessions ends, the phone disconnects and reconnects, but once you run adb shell again, you still have the $ prompt, and no root. No error messages appear.
In both cases I made sure USB debugging was enabled. I haven't tried superoneclick yet, but according to what I've read from others it doesn't work either. I'll download and try it anyway.
Thanks for your help.