$299 for an unlocked smartphone on NO contract, on lead device hardware, with the newest Android OS (and which will receive updates as soon as they're ready), and solid reviews?
And it's not just that you'll get updates--you'll also be able to grab the source directly from the Android site, make any tweaks you like, and build your very own image for your phone. You should be able to run bleeding-edge Android as it goes into the repo if you feel like living dangerously. It beats the usual "Well, we might get a Cyanogenmod ROM... maybe" for other phones.
source.android.com has build instructions for the stock distribution; you just need to figure out what the device name for your phone is (Nexus S == "crespo", IIRC) and specify that as the target to "lunch". You'll get a zip file you can then flash to the phone.
Yikes!!