Samsung had promised to release Froyo for the Galaxy S by the end of September. However, the good news is that with a little bit of trickery you might just be able to get Froyo on your Galaxy a lot sooner than that.
Multiple XDA forum members are reporting that it is possible to get Froyo running on the Galaxy S through Samsung Kies. The trick is to set Kies to test mode (CTRL+ALT+U+P) and modify the Windows registry. Please note that this might crash your handset and force you to do a factory reset.
Although Samsung appears to have fixed the extremely annoying GPS bug that plagued many of the earlier Galaxy S firmware builds, the jury is still out when it comes to performance improvements. However, it might be futile to rush to a judgment, as this is most probably not a final build of the firmware. Nevertheless, this does signal that the official Android 2.2 update for unbranded Galaxy S handsets will arrive soon.
Hat Tip: @kalpik