So are you saying google developers do NOT have a project with the samsung galaxy and trying to update the OS? because that would be more than just updating the source code I am sure. Imo samsung is just the middle man here and with middlemen you can cut them out of the equation. and who is to say that it costs to upgrade the OS? Is it not open source or what? it is only software they are updating its not like its a total new phone creation although samsung did create a new android already with touchwiz and 2.1 but thats for south korea.
So much misconception...
As already mentioned Google has no hand in GAOSP - the project is only hosted on a website provided by them, but the site is run by the community. This is just like having a GMail account - it doesn't mean that Google endorses or writes your email, you just get to use it and store your messages there.
Samsung is a "middle man" in a sense, but they cannot be just cut out that easily. The BH2 relies on proprietary software to operate, so unless some one reverse engineers it (which the community is trying to do) Samsung must be involved.
Of course software upgrades cost money - code does not write its self! It costs in time not spent on other projects that do make money, and it costs in wages paid to the programmers. In fact, the largest organizations in open source (Canonical, Novel, Sun [RIP], IBM, Red Hat, Google, etc - and many of the smaller ones) are for-profit businesses. Just because you may be able to get it "for free" doesn't mean money wasn't spent to make it.
Additionally, Android is only open source in the way that "anyone can use and change it for themselves", not that "everyone can contribute to official development". Android is made solely at Google's expense. It is only after they are done with a release that they give us access to the source code.
I see no reason to think the BH2 won't be officially getting 2.1 eventually. We've been hearing this from various sources for a few months, but we are letting the delays and anticipation get to us.
As for 2.1 reaching the other phones - technically it should be possible to create a "slim" release without the power hungry addons and extra applications. The issue is whether or not the OEM's will publish the update. Personally I'm taking the news no further than that Google has internally demonstrated a build of 2.1 on low spec devices and is trying to convince the manufacturers to use it. Regardless, the final decision is still in the hands of companies who are may be more concerned about next year's device line up than last year's.