Guys wanna upgrade ur Optimus one to Android 2.3.....

Flashing Cyanogen Mod to LG Optimus One

This July is the expected month for the release of Gingerbread 2.3 update from Google for the LG Optimus One. One option that you could try instead of taking on the Google's update is the Cyanogen mod 7 which impatient android users has been installing since its release. Basically, it runs on Gingerbread 2.3.4. Though it has some minor bugs, I have been using it and it is still a thumbs up for me since it made my phone snappier.

Note: It is a must to have your phone rooted (I did it with z4root but you could also try Gingerbreak). You can download the app here.

1. Download the latest stable version of the ROM from the XDA Developers. Go to unofficial Cyanagenmod 7 thread or if your phone is supported by Cyanogen Community Go directly to their website and download your phone's version. Don't worry it is being kept up to date by XDA. Download also the GAPPS.ZIP here for installing the Android Market and Google Apps.
   
   
2. Download, extract and copy the files below to the root of your SD card.
flash_image
recovery-RA-GNM-thunderg-1.1.0.img
3. Download terminal emulator here and install it in your phone. This lets you run Linux command line utilities on your Android phone.
When you open Terminal Emulator and type “su” without the quotes it will ask you for superuser access. Grant the app superuser permission by selecting YES. Now you will see a # sign.
Type all the commands given below without the # sign

# mount -o remount,rw -t yaffs2 /dev/block/mtdblock1 /system
# cat /sdcard/flash_image > /system/bin/flash_image
# chmod 755 /system/bin/flash_image
# mv /system/etc/install-recovery.sh /system/etc/install-recovery.sh.bak
# mount -o remount,ro -t yaffs2 /dev/block/mtdblock1 /system
# flash_image recovery /sdcard/recovery-RA-GNM-thunderg-1.1.0.img
# reboot recovery
The command highlighted in red will show error in some phones. Just Ignore it. Its  normal.
After successfully executing all the commands your phone will boot into Custom Recovery mode because the last command was “reboot recovery”.
To boot your Phone into Custom Recovery mode anytime, switch off your phone and press and hold the vol_down + home + power buttons.

4. In the recovery menu, select Backup/Restore, then select Nand backup.  What this will do is backup your current ROM on your SD card, if something goes wrong while flashing the new ROM you can simply boot into recovery and restore your previous ROM. Custom recovery menu will look like this: 
5. Connect the phone to your computer and inside Recovery main menu click the option ‘USB-MS toggle’ and then ‘USB-MS Toggle SDCard’. This will unmount the SD card so that you can see it in your computer. Backup everything from your SD Card. Eject from computer and toggle USB again from recovery to mount the SD card back in phone.
6. Though it is not a necessity for this ROM, I would suggest partitioning your SD card to create swap and ext partitions. The ext partition will come in use if you want to install apps onto your SD card later. This is different from what you see in Froyo versions of Move to SD option. Partitioning will format your SD card, so make sure you backup your SD card as mentioned in Step 3.
7. Go back to the recovery menu again and select ‘Partition sdcard’. Then select ‘Partition SD’. Create a swap partition of size 0 and ext partition of size 512. Once done hit Back to go again to the ‘Partition sdcard’ menu. Convert the partition you just created to ext 3 and then ext4 using the options ‘SD:ext2 to ext3’ and ‘SD:ext3 to ext4’.
8. Toggle USB from recovery again. Inside the SDcard copy the ROM you downloaded in Step 1. Once done, eject the SD card and toggle USB again to mount the SD Card in the phone again.
9. Go to the Wipe option in the recovery menu and wipe userdata, /data, /sd-ext, /sdcard/.android_secure, /cache, ‘Dalvik-cache’
10. Then go to the Flash Zip option in the recovery menu and select the zip file you copied in Step 8. Do this to both of the zip files.

Just wait while your phone finishes its flashing/installation. After the flash is complete, reboot your phone from the recovery menu. Now you can enjoy Gingerbread 2.3 on your LG Optimus One P500.

Android Market will only appear after setting up your google account.