Android OS 2.2 (Froyo) seems to be gaining a lot of attention lately and all positive ones. Based on the latest pic (by Engadget, Froyo has the USB tethering and WiFi Hotspot function. I love these functions and it is a must to have them for my future phones, at least.
Apart from that, did you know that Froyo is fast. A post by Gizmodo recently shows that when compared with Android 2.1 and Android 2.2, Android 2.2 is 450% faster!