According to Joe Strauss of the St. Louis Post-Dispatch, the Cardinals took note of the recent sign-and-trade allowance by MLB. They’re said to have a "passing interest" in Juan Cruz. Wouldn’t hurt to add another power arm to the bullpen if the price is right.
Strauss doesn’t say it, but the Cards could also look to pull off a sign-and-trade for Orlando Hudson (pure speculation on my part). The Cardinals have not been linked to Hudson in recent days; the Dodgers and Royals are the rumored suitors.