Ripple is a scam to make OpenCoin rich off of other's evangelism. Luckily for them, it seems to be working.
That's not that simple. Their technological solutions are quite complicated, there were a lot of thinking and coding involved, so it's not a Ponzi scheme, they did some real work and plan to open source it for free, so anyone can easily create competing forks.
So I wouldn't call it a scam - it doesn't look like that.
They plan to open source it for free when they are confident that a fork won't be successful (not that it will work). There was a lot of thinking and coding involved (except for how the system could work without a centralized currency), but not enough to be worth every XRP in existence. Is Satoshi's contribution to Bitcoin worth every Bitcoin in existence? It takes a lot of work by many people to make a currency popular. Ripple promoters are basically acting as slave labor on behalf of OpenCoin for a paltry sum of XRP. There are more kids looking to get rich quick than brains in the cryptocurrency community.