No as ripple isn't decentralized at all. A single server processes all transactions. Take down the server, take down ripple. Their system doesn't work.
It's not decentralized NOW, because OpenCoin is the only one running servers. But they have clearly stated their long term plan is to open-source the server. The system is definitely designed to be decentralized.
OK. Servers might be decentralized, but if we decided we wanted something changed, could we distribute a patch to 51% of the network and fork the code? If no, it isn't decentralized in the slightest.