As with most other Android phones, the LG Optimus S didn't remain a rooting virgin for long - in fact, it was only a matter of how long it took Android Central forums member KSmithInNY to get the device out of the box.
Before getting started, you'll need to download the Sun JRE (or should I call it Oracle now?), the Android SDK, and drivers for the Optimus S (model LGP500, here's a detailed guide on installing those). Once you've got those, here's how to go about it:
Step 1: Plug your phone into your PC with the USB cable.
Step 2: Make sure the phone is charge only (don't mount as USB drive) and USB debugging is enabled. Menu > Settings > Applications > Development > check mark USB debugging
Step 3: Launch the SDK manager, should be something like C:/Android-sdk-windows SDK Manager
Step 4: Open a CMD window and type the following:
cd c:/wherever-your-sdk-tools-folder-is (mine for example is C:/android/tools)
adb push rageagainstthecage-arm5.bin /data/local/tmp/rageagainstthecage
chmod 4755 /data/local/tmp/rageagainstthecage
./rageagainstthecage (let things sit a couple minutes (2), your phone will disconnect from the computer and you'll be removed from your ADB session)
This should return a "#" symbol instead of a "$" symbol. If it does you're good. If not go back and start step 5 over
Step 5: Go to the android market on your phone and download "Superuser"(free). The developer will be listed as ChainsDD. Do the following:
-Open the Superuser application after it downloads
-click the settings tab in the top right corner of your screen
-scroll to the bottom of the settings tab and click the very last button. Should be a binary button with "tap to check for updates"
Step 6: Go back to the market and download "Titanium Backup" (free version). Do the following:
-Open the titanium Backup application after it downloads
-grant it Super User permission
-You should have a pop-up screen in front of you and one of the buttons on the bottom should say "problems". Click that.
-You can now delete titanium backup although the developer is a great guy and we recommend you consider purchasing the full app.
It's not as simple as could be yet, and support for OS X users still isn't there - but for a device that has yet to be released, it would be hard to complain.