a) Ripple is centralized (owned by a few) even if their system is built on P2P
Yeah, sadly currently it would appear OpenCoin, inc is practically the government that hands out their ripples (XRP) like charity and saves a bunch for themselves. I haven't even been able to figure out how to get my hands on a ripple without begging for it from someone who has some (like the dude at the park in the movie Falling Down
http://www.youtube.com/watch?v=FwP2vV6Wm1Y )