RE: Nexus, yeah we've pretty much learned by this point that it's gonna be Samsung again. Also Andy Rubin recently mentioned that there's a "bidding process" as to which OEM gets to make each Nexus device.
Unfortunately we don't know what that process entails but it's most likely a combination of who can make the best spec'd and most impressive demo hardware, combined with what promises they make to Google (as far as their continued commitment to both Android and the OHA), and flexibility. For example, we already know that Google is working closely with Texas Instruments for Ice Cream Sandwich, the implication being that the ICS launch devices will be OMAP-powered. Nexus Prime leaked info indeed fits that bill, but Samsung would have had to go out of their way to make that happen because they usually use either their own processors (like the Exynos in the SGS2) , or NVIDIA ones (like the Tegra 2 that's in the Galaxy R and other devices). Not that Samsung haven't worked with TI before, they have, it's just a less common occurrence.
At one stage it was reported that HTC, LG and Samsung had all submitted demo hardware for the Nexus bidding process.
I think Samsung is definitely the right choice though. Their sales are through the roof, they've tied up deals with more carriers than anyone else, and most importantly they are making the best products right now. Pretty much every major tech blog - even the ones who have traditionally been more Apple-biased - have stated that the SGS2 is the best phone in the world right now, bar none. Having owned mine for 6 weeks now I have to agree because I simply cannot fault it in any way. I can't make even show a trace of lag even when I try to push it to the limit with CPU intensive apps, and updating well over 25 apps in the Market simultaneously. And the screen is just amazing.
You bump all those specs up even more - Nexus Prime is rumored to have a bigger screen, an even more improved display technology (Super AMOLED Plus HD) with a full 720p display resolution, a 1.5GhZ dual core processor, and of course Ice Cream Sandwich and you've clearly got a beast of epic proportions. I really think rival companies are gonna have to pull every last trick out of the bag to even compete.