Is that when you pray to (or is it through...) a Saint, rather than directly to God [qm]. Apologies; I'm largely ignorant of internal RC stuff.
Theres nothing distinctively Catholic, as jmfcst rightly says (probably my only use of those three words in that order) in praying for either the living or departed.
Intercession through the saints however may be more debatable; that is the 'petitioning' to God through saints, often specific saints on behalf of yourself or others. Often, and this is controversial within some Catholic circles, is praying for intercession through non-canonised people of note or worth. This can all get mixed up in whether or not the dead can infact pray for the living etc.
Many Protestants believe that there is no 'mediator' between man and God (and I think there is something in Timothy about that)