No, they don't acquire support against US dollars. They both stand on different platforms. But some banks, those who want to avoid the delay in transaction and want a faster process, have started to use Ripple recently.
You should recheck your sources as there is no bank at the moment who holds ripple who has any usage in the Ripple Labs network.
There are plans to do so in the future, but it's nothing more then just rumors.
About the connection between USD and Ripple, there's no connection actually, and the price of ripple is basically being driven by the correlation of BTC and other altcoins.