Samsung Galaxy S I9000 update for Android 2.2.1 is available through Kies
However, it doesn't appear to be rolling out to all region from the onset, rather, users in Sweden report that they're seeing it being pushed through Samsung's desktop application Kies. The upgrade actually addresses some stifling lag issues seen with the device and patches up some other bugs and security glitches. In fact, owners who upgraded their handsets report that they are experiencing a significant boost in speed now.
Granted that Sweden is the first to get in with this new firmware update, there is no concrete indication on when other regions will start to see it as well - but you can only hope it'll be swift.
source: SweDroid (translated) via Androinica