The Android 2.3 Nexus S (T-Mobile in the US) is going on sale today for $199 with a contract and $529 without. The phone is NFC-enabled, which isn't meaningful to anyone right now because there's no NFC infrastructure for users to tap into. But it will be a feature of Android going forward. It also suggests Google's future intentions with regard to ads and payments on mobile devices.
Overall the handset is the best and most elegant and fully realized of the Android devices on the market (until the next one comes out next month). My HTC EVO is a "tank" by comparison. (I could put it in a sock and kill someone with it.) I'm not a fan of the "green" Samsung display however. I've been using it for the past week and really like the device. There's not much to criticize. I would buy one in a heartbeat if I didn't already have my EVO.
I haven't noticed many significant differences, beyond NFC inclusion, between Froyo and Gingerbread. It is however less "substantial" than its N1 predecessor and feels more like a "generic" Android device than a uniquely Google device (in the way the N1 felt different).
The differences between the iPhone and Nexus S are fewer than earlier and other Android devices -- the keyboard still under-performs (Swiftkey is still a must). But it's a pretty compelling handset overall. And for those who are heavy users of Google services, it's arguably better bet than the iPhone.
The two big differentiators for Android (vs the iPhone) are Navigation and Voice Actions. The iPhone has voice search and various alternative navigation apps and tools. But the integration of Google's services with Navigation is pretty compelling (never mind that directions are poor sometimes).