The Samsung Galaxy Nexus' specification and design had already leaked well before the event, so there was little to reveal for Samsung. The display is the most interesting aspect of the device - a beautiful 4.65" Super AMOLED+ 1280x720 display. You may think this makes the device far too large - but thanks to its thin bezel and the fact that the display's height accounts for most of the size increase the phone itself isn't larger than current Android devices with 4.3" or 4.5" displays.
For the rest, the Galaxy Nexus sports a dual-core 1.2Ghz processor, which I actually find a little on the slow side for what is supposed to be the flagship Android device. I'm assuming the relatively slow processor (compared to the 1.5Ghz processors which are popping up all over the Android ecosystem) has been chosen to not stress the battery too much. That large display needs juice, after all.
The Galaxy Nexus will be available starting November, all over the world. In true Nexus programme tradition, it will be the first Android phone to ship with the newest Android release - in this case, Android 4.0, Ice Cream Sandwich.
Ice Cream Sandwich is clearly not a revolutionary release in terms of features. There is some cool new stuff in there - like a Windows Phone 7-like People App (basically a 1:1 copy of WP7's People Hub), and the facial recognition login technology - but that's not the focus here. No, the focus is streamlining and prettifying.
Virtually all of Android is getting a visual overhaul, with a completely new visual style - sharp, minimalistic, and surely with a firm dash of Metro (hey, no complaints from me, Metro is awesome). Google said they don't want Android to adopt the fake wooden planks and brushed metal nonsense of 'some other mobile operating systems' - and I couldn't agree more. iOS' Microsoft BOB-like My First Operating System-like approach to application design needs to die a slow and horrible death, and I'm happy Google is following in Microsoft's footsteps, away from that silly style.
Ice Cream Sandwich also introduces a new font, Roboto, which is the default font all throughout Android 4.0. It's designed for high-density displays, and, as always with anything that isn't ZOMGHELVETICAGGNRFFRRRR, the font hipsters are hating on it like crazy. Of course, had Apple used this font, it would've been awesome and beautifully elegant and understated and magical (how's that Comic Sans rip-off Marker Felt that's infesting iOS working out for ya?). Alas, I like it, I think it looks nice. It's certainly not as beautiful as Metro's excellent Segoe-based typography, but then again - nothing is.
Other than just a visual overhaul, user interface behaviour is also being overhauled to make the process of using Android. It's a little difficult to explain, but when watching the demonstration, it became clear several tasks were just easier and faster to accomplish due to redesigned UI behaviours, different widget placements, and tighter integration. I especially like how the swipe-to-side gesture is now the universal delete/kill/close gesture (tasks in the task manager, tabs in the browser, etc.).
As far as release dates and updates go, Google said any Gingerbread device should be able to run Ice Cream Sandwich as well, but as usual, it will all depend on the device makers and carriers (and ROM builders, of course). There's no release yet, and thus no source code - there is, however, the SDK.