DO THIS ON YOUR OWN RISK, I WILL HAVE NO LIABILITY IF YOU BRICK YOUR PHONE !!!
Read instructions carefully
First of all, download archive from here and extract it to your desktop
And download driver pack from here
1. Back up all data with ASTRO file manager, you can find it on market.
2. Hard reset your phone either with system->privacy->erase all data or turning your phone off, and holding HOME,VOLUME DOWN and POWER BUTTON.
3. After phone boots up, you have clean file system, then go to Applications, and turn on USB Debugging mode
NOW THE FUNNY PART
1. Connect your phone with usb cables, make sure you have installed all the drivers needed, and connect phone in DEBUGGING Mode (provided a bit upper on this post)
2. In the extracted folder called root on your desktop, go to ADB folder and start cmd7.exe if u run win7 or cmdXP.exe (run as administrator in both options) if ur pc runs win XP. (your address bar should like something like this: C:\Documents and Settings\YOUR NAME HERE\Desktop\root\ADB
3. After starting cmd7 or cmdXP, type following commands
echo 1 > /data/local/lge_adb.conf
5. After reboot, go to root folder on desktop again, and start SuperOneClick.exe
6. Select GingerBreak method and press root button
7. After few seconds VOILA !!! You have rooted Optimus One.
8. REBOOT PHONE and update superuser app from market (mine was updated automatically)
To unroot device, follow steps from 1 to 6 in FUNNY PART and select unroot instead gingerbreak. and you will have unrooted device
I tried to root all kinds with android SDK and many others, and always had problems with force close. Running on this method for 3 days, and have no errors.
This is my tutorial, if u consider it helpfull, think about donating for cofee or beer.
Comments, Questions... post it below, i will read them and answer ASAP
EDIT : If you want to have beautiful CRT OFF Animation on your phone read tut here be sure to backup phonebook mine was deleted, but now i have crt off animation, which i looooove and think that is the second best thing to do after rooting
VIDEO IS LOCATED HERE