A Samsung phone with model number GT-i9023, which is very close to the Nexus S' model number of GT-i9020, has just passed the FCC with T-Mobile's band (AWS 3G). On top of that, German site BestBoyZ has posted a video of a Nexus S in the wild running Android 2.4. The baseband version in the About screen includes the text i9023.
Assuming there is a new Nexus S that will ship with Android 2.4, we have to wonder whether the new device will have any hardware improvements over the current device. It's possible that Samsung is going to use version 2.4 as an opportunity to tweak the Nexus S to add HSPA+ for T-Mobile, but hopefully it will change more than that.
Last month, Google officially introduced the Nexus S at the same time as Android 2.3 (codenamed Gingerbread). The Nexus S was the first device to ship with Gingerbread; Google and Samsung developed the product together to highlight the latest advancements of the Android platform. As the Nexus One before it, the Nexus S delivers a "pure Google" experience: an unlocked device that is the first to get the latest updates to Google's mobile services and Android releases.
Android 2.4 is rumored to be shipping this summer. After screenshots of the new version leaked last week, we already have a leaked video confirming them! Maybe version 2.4 will come sooner than expected?