T-Mobile has finally released the Android 2.2 update for Samsung Vibrant, it started rolling out as it was earlier rumored. Apart from the usual FroYo goodness, which includes Apps on SD card, Wi-Fi tethering, update also brings Wi-Fi calling on T-Mobile Samsung Vibrant.
You can download the update via Samsung Kies Mini. The update is build number T959UVKA6 also known as KA6. Full instructions on the update are available on T-Mobile site.