DividendRippler can be "anonymous" obviously only because it stays in crypto-land exclusively and doesn't deal with any fiat and the banking system.
Bitstamp only for verified members
I believe that many Bitstamp members who are concerned about their privacy will transfer their funds to Ripple network, Bitstamp is already connected to Ripple and it's a matter of seconds to transfer funds from Bitstamp to Ripple.
Except that you can't physically "transfer" any funds from Bitstamp to the "Ripple network". The funds are still in your Bitstamp, they only set a flag that you see them in your Ripple account rather than your Bitstamp account.
It's only when you connect to a second gateway that a Bitstamp USD IOU can be auto-magically converted into the other gateway's USD IOU, because that's what Ripple does. However, you'll probably have to get verified by the other gateway too.
And if you convert your USD IOUs to XRPs (in case that's what you mean), well people can convert them to any crypto-currency really. XRPs even have an enormous disadvantage regarding this, because Ripple is not made for privacy; your Ripple account is an open book, public for the whole world to see. And your Ripple account is immediately tied to your verified Bitstamp (or other gateway) account. So Ripple will not pass the "Donations to Wikileaks/Snowden" Litmus test.