Overall, Fontenot was batting .364 with six home runs, 10 doubles and 27 RBIs in 35 games with Iowa this season prior to being called up.
"He's surprising, and he's a little guy that's strong," Iowa manager Buddy Bailey said of Fontenot (5-foot-8, 160 pounds). "He has some pop and a chance to hit a lot of doubles. You look at his body size and think he might be restricted to a singles hitter, but he's not.
"He's got some surprising power for a little man."
Fontenot entered 2007 a career .287 hitter with 42 home runs, 120 doubles and 243 RBIs in five minor league seasons.
The Cubs acquired him from Baltimore in February, 2005. He was an Orioles first-round draft pick in 2001 from LSU.
Through 13 games this month with Iowa, the 26-year-old Fontenot was batting .471 (24-for-51). From May 7-13, the period in which he was named the Pacific Coast League Hitter of the Week, he tallied 18 hits in 31 at-bats.
To coincide with Tuesday's move, RHP Rocky Cherry was optioned back to Triple-A. The 27-year-old right-hander was 1-1 with a 2.89 ERA in eight relief appearances for Chicago.