How to preserve anonymity within Ripple? The common practice for cryptocoins like Bitcoin is to limit address reuse to preserve anonymity. This is achieved by sending the "change" of a transaction to another address and using a unused address for every transaction. (Research showed that even when best practices are used identities could be derived but that's not the point here).

The Ripple wiki documents something about an Account Familiy which seems comparable with Bitcoins deterministic wallets as decribed in BIP0032. However the Ripple system requires a fee for account-activation. 

When using an account family how does one activate such account and how does (I presume) rippled know that an account from a family is activated?
Note, anonymity isn't a design goal for ripple. Depending on the level of pseudo-anonymity required, gateway and future features of Ripple would likely be easier (and more cost effective) than using many Ripple addresses (aka Ripple accounts).

To tell if two (or more) Ripple addresses are in the same family you need the public generator (which is named for generating the public keys, it should not be made public). Without that no one can tell if they are part of the same family and therefore they are funded/activated independently exactly like any other address is (someone sends it the XRP account reserve).

I'm not aware of any Ripple client that currently implements account families (the existing clients just use the public and private ECDSA key corresponding to index 0 within the account family).