The Astros have agreed to a deal with 21 year old Cuban pitching prospect Carlos Sierra, according to this Houston Chronicle article. Because the transaction is subject to international signing rules, the cost is not expected to be very high. Although Sierra may not be a top rated prospect, the Chronicle says that the Astros are high on him. A previous MLB.com article on the righthand pitcher states:
In addition to his fastball -- thrown at three different angles -- Sierra also throws a slider, a curve, and a circle-change. He played three seasons for Sancti Spíritus in Cuba's Serie Nacional and for the island's 16-and-under and 18-and-under national teams...
Unlike most Cuban prospects, Sierra did not have to defect in order to become a major league prospect. Due to his grandfather's roots, Sierra was granted Spanish citizenship and has been playing for a Spanish baseball league on the Canary Islands.
The Chronicle suggests that he will start in the A-level of the Astros' minor league system.
And, while we're talking about Cuban prospects, have you read about the young phenom, Lazaro Armenteros? This article paints a picture of a youngster who may be a Bryce Harper type prospect. He has not yet become eligible for MLB free agency, but he will put on a show for scouts next month. Presumably he will be quite expensive, so we don't know what the Astros' chances would be. However, it's interesting that the field of suitors will be cut down somewhat because the Yankees, Angels, D-Backs, Red Sox, and Rays will be ineligible to sign him because of international pool violations.