I don't think the government would allow Goldman Sachs to create a for-profit private currency. In fact, I am a little bit surprised that they've accepted Bitcoins to the extent they have. It might very well be that there will eventually be a total crackdown on private currencies. But I think that in general governments would view private currencies created by charitable organizations more benevolently.
How to get the whole thing rolling is a hard but perhaps not unsurmountable problem. The problem is of course that a currency that no one else uses is not very useful. On the other hand, if lots of other people use a currency then it's very useful. So currencies have a winner take all structure.
I can think of two groups that you would try to market this for. The first is altruists and charity organizations, which would have an interest in using the currency if they knew that that benefited another charity they trusted. The second is the people who are interested in Bitcoins for whatever libertarian or other reasons (minus the criminals).
In the last few years we have seen two interesting revolutionary ideas on how to change the monetary system. The first is Bitcoin: the most well-known peer-to-peer currency. It has been wildly debated recently and I won't go into the detail of allegations of use in criminal activities etc (for one thing, I don't know much about it). My interest is rather in the money creation part. The people who run the Bitcoin software are rewarded for their work with new Bitcoins - a process called mining. Now the pace at which new Bitcoins are mined is limited, which means that Bitcoin creation is a zero-sum game: the more one miner contributes to the Bitcoin software, the less Bitcoins other miners get. Unsurprisingly, this has led to an arms race: miners spend nearly as much on running the software as they get back in form of new Bitcoins.
The second idea is the Chicago Plan, which was debated already in the 30's, after the great crash of 1929, but which recently was resurrected by Michael Kumhof (senior economist at IMF, of all places). The central idea of the Chicago Plan is to abolish fractional reserve banking - the system by which private banks in effect create money out of thin air. Instead of lending out most of the depositors' money, banks would effectively have to let them stay in the bank.
Instead money would be created by the central bank/government, a process that would generate a massive seignorage for the government. According to Kumhof, it would also have other beneficial effects, such as killing off the "boom-and-bust"-cycles which he thinks fractional reserve banking are mostly responsible for, and diminishing the wasteful parts of the financial sector.
Kumhof ideas' have not been well received. Overall, it is remarkable how little reform there has been of the financial and monetary system given that the world had a major financial meltdown 2008 (and was close to an even greater one, in my understanding). Governments won't challenge the financial system radically in the near future, that's for sure.
Instead radical reforms can only come from private hands. Let us now compare the two ideas. In the Bitcoin system money is created by private hands, but in wasteful ways, which effectively means that there is very little seignorage. Under the Chicago plan, money is created by the government in much more efficient ways, which leads to a large seignorage. Now my idea is to take the best part of both of these ideas: let a private player - more exactly, an altruistic organization such as CEA - produce the money centrally, Chicago plan-like, and let the seignorage be used for altruistic purposes. (Of course, there would be some costs of running the system, but if the system was sufficiently large, these would be negligible in relation to the seignorage.)
If the altruistic organization that did this had a sufficiently good reputation, chances are greater that people would trust the system. Of course, it would try to stop the currency from being used to launder money, drug trade etc.
Generally, people would be suspicious of private currencies where the central authority collected a seignorage, but if this seignorage was used for charitable and other altruistic purposes (and people really trusted that that would be the case), this would, I hope, be less of a problem.
What do you think? I'd be happy to get comments from people who know more about the Bitcoin system, since I don't really know it (though I find it interesting). Perhaps there is some info concerning Bitcoins that tells against this proposal; if so, I'd be interested in that.