The historic Samsung Galaxy S (GT-i9000) already can be upgraded to the latest Android 4.2 Jelly Bean with a cooked ROM thanks to XDA developers.
This is a preview build based on AOSP, which enables you to experience all the new features of the latest version of Android. This is the first Jelly Bean 4.2 ROM available for Galaxy S and therefore there are some features that are not yet quite polished and other things that do not work. For example, some users have reported not working the WiFi, APN and neither has Email / Exchange application.
However, its developer claims that almost everything works: RIL, Data, WiFi (to some users do not work as just mentioned), camera, audio, GPS, TV Out, December, etc.
It may not be a ROM for everyday use, but if you like to experiment with your Android may be a good opportunity.
Here is the installation process described by pawitp:
It should be noted that from AndroidADN we are not responsible for any damage that may occur to your device during this process. It acts at your own risk.
Note: This ROM uses the same partition layout of CM10.
- Make a Nandroid Backup!
- Install the ROM using ClockworkMod Recovery
- If you wish you can install the Google Addon (install every time you install the ROM as currently no backup system)
- Optionally install SuperSU
More info on XDA