Well as the header already mentions. What about "Tales of the Quaesitors"? Is it still in development?
What was it? Where did you here if it?
Yes, "magic shoe" 
Sadly, nothing new then. I'm always interested in new Ars Magica content.
However, it's easy to incorporate the gumshoe idea into ars magica. Just the simple game-mechanic of any gumshoe system really improved my game in the more mystery related stories:
"..that you shouldn't roll to receive a clue, but you might have to roll, to find out how your character would interpretate a certain clue."
".. that you don't have to roll for clues at all regarding the fields of knowledge your specialized in."
I started incorporating Gumshoe mechanics into my non-Gumshoe games since first reading Trail of Cthulhu. Since most of my RPG campaigns revolve around mysteries and investigation Gumshoe has served my gaming groups well.