According to the Enquirer:

Article says it’s basically a signing for 2011 as he’s getting ready to have surgery for a torn ulnar collateral ligament in his pitching elbow. Doesn’t give any signing details (length, amount, etc)…

Walt Jocketty said:

    “He’s a young guy with a power arm,” Reds general manager Walt Jocketty said. “We think he’ll fit in our bullpen when he’s healthy. We’re trying to stockpile those power arms.”

The article talks about his past two seasons with the Angels:

    Arredondo, 25, went 10-2 with a 1.62 ERA in 52 games in 2008 with Angels. He led both leagues’ relievers in victories and opponents batted only .190 against him.

    He slipped to 2-3 with 6.00 ERA last season in 43 games. He dealt with the elbow problems all season.

Since the article says it’s a deal for 2011, I assume it’s more than a one year deal and since it’s a minor league deal, I assume it’s not expensive, so…sounds like a good signing to me.